How to know if a recruitment offer is a fraud

Don't believe in such rackets. There are group of people targeting the innocent youth people to extort money by arranging fake interviews. Actually their modulus of operandi is to lure the unemployed with a set of questions posing to be on the Board of interview. The group consists of fake people posing to be a Receptionist, a Typist, a few fake people on the Board and at the end of such a fake interview, you may be intimated regarding your selection for a particular post extorting a heavy amount of money.
They take the unemployed into their confidence so that they are badly entrapped in their rackets resulting in massive loss of money.
However, with a prudent approach such fraudulent situation can be averted -
1) In case, you get a call from such a fake interview, search the same in the Google if the same company is operating.
2) Go through the appointment letter as provided by them and see if any registered number is appearing on the appointment - letter.
3) Take the feed back of local people with a detailed query of the existence of such a firm.
4) If the racket is going on Continiously for a couple of days, inform Police of that locality so that they may tackle with the fraudsters with an effective way.

I haven't found on google either nor any registration number on slip just a contact number help line I asked the madam to give me her mobile phone number she didn't agreed and told me there is a helpline number
(hidden information) and the guys I was talking to (hidden information) kindly help me what should I do to get my money back and to stop them.

It is not advisable to go for job interviews where you are asked to pay money for getting a joining letter. You could have made proper inquiries before handing over any cash. Did you even get a proper receipt for the first payment of Rs. 200/- and the later one of Rs.600/-? You should have demanded the money back when you were told it was non-refundable and said you were not interested in the job.

The whole scenario is suspicious. Who was the person who informed you of this job? Was it anybody you knew closely? If not, never accept calls from unknown persons about vague job offers. Was there really a written exam? Why the emphasis not to talk to each other? Generally, it is normal for candidates waiting outside to have quiet conversations with each other.

On looking up online the address where you went, it is possible this is a rental space taken on a temporary basis. I am having my doubts about whether it was a genuine recruitment agency. The 'info solutions' part of their name is a common one used by many so-called consulting and job-hiring agencies. The fact that they gave you just a slip of paper and not a definite job offer as such or details of which company you are being hired by, the job responsibilities, etc indicates some kind of scam. Does the slip of paper have any contact person's name and numbers?

I suggest you don't wait for more people to get duped if indeed it is a recruitment scam. Visit the nearest police station and state your case, suggesting that you think it seems to be a scam and would like help to know if it is a genuine recruitment office or would like to get back your money. As per the address which you have given, it seems the nearest one is the Bow Bazar Police Station. Make copies of the slip of paper which you got from them (retain the original with you) and provide the contact number of the person who called you about this job offer. If the police are helpful, they can find out who is the owner of the premises and to whom it was hired out, who these people really are, etc.

After submitting my advice above, I saw your response wherein you have given the contact phone numbers. Provide these numbers to the police. They will trace it out (the first seems to be an Airtel number) and find out in whose names the numbers are registered.

These days many people are getting trapped like this. They are trying to exploit the unemployment problem in our country. Never believe this type of interviews. To attend the interview also we should insist on a letter from the concerned company on a letterhead wherein the name, address and telephone numbers of the Organisation are written. These are all false and no one should believe such people.
Don't pay further any money and based on the Phone Number they have given you can try to trace back the person by taking the help of the local police. Lodge a complaint and give the address of the place where you went for attending the interview and give as many details as possible.
Many phone calls are also coming these days saying that there are many jibs and salaries very high and they will ask us to register our name with them and ask us to pay a few thousands of rupees as registration fee.
I also received a call and asked me to register. I told I will not pay a single rupee also now. After getting the appointment letter and after I join and get my first-month salary, I will pay him a full month salary. He says his company rules will not accept that. Then I told him that I never asked or requested him to get me a job and as such he can forget about me and I never paid the registration charges.

You may approach the Police -station providing the details of the mobile no already given to you. It would be easy to ascertain the service - provider with a little exercise from the Google NET. However, to nab the the gang, let the task be undertaken by the Police.
Your refund of money from the said dubious company seems to be a herculean task at this moment.

Internet is a source of good information but at the same time some fraudulent people are using it to trick the gullible people and exploiting them in the name of a job or vacancy. We should be alert in this respect and not fall prey to these miscreants in the internet.

Whenever such a call is received then first thing is to find out is genuineness. For this some research is to be done in the internet itself like finding the name of the company mentioned by the caller, getting information about it etc. Reputed search engine like Google or Yahoo are to be used for this purpose. Never believe the information received on a phone call. If you are asked to pay a registration fee never pay it. No job portal asks for money for job information.

Please note that we are in an age of competition and there is a high demand of jobs and whether job is good or ordinary does not matter. There is a beeline for all sort of jobs today. In such a situation why someone will call you or send you an email and offer a job so easily when thousands of better qualified and able people are available to him in the market. I think we must be very cautious about such people who are making us fool and getting some money by doing that.

Though this answer particular for this question, the suggestions may be applied in general by others also.

1." I got a call from a person telling me that there is a vacancy"
Did you register with the agency who called you? If not that itself is a signal that things are not direct and straight. You can take that they got the data about you from some other sources.. First ascertain who they are. Ascertain for whom or on whose behalf they are calling. If you are satisfied then you may proceed with caution and alertness.
2." We were told .... not to talk to each other."
This can be a normal procedure as they don't want the candidates to know what questions are being asked. But it can also be taken as an alert that things are not very transparent.
3 "Then she told me I need to pay Rs.800/- for direct joining letter. And Rs.1500 for training and if want to level the job, then I need to pay the company the three-month salary. "
This is where you should sense danger. A needy employer wills never ask for money from prospective employees. They may ask for some security bond or service bond in case the job requires cash dealing etc
If it is a recruitment agency, they would have asked for a registration fee and given you a reference number, profile number an time limit for the validity.
In the present case it is not such and smirks of duping.
I suggest you not to pay anything further and not to contact them. Take it as good riddance.
No good organisation will collect any money from job candidates. Good Recruiting agencies may collect a small registration fees. Some private agencies may ask for a percentage of first month salary or some fixed amount if the job is obtained. But that will be given in terms and conditions at the time of registration itself.
Be alert and vigilant before replying to unsolicited job calls. Also verify genuineness of recruiting agencies before registration itself.
In the present case it is not suggested to comply with their request for money.