1. Frankly speaking, I don't know anything about kanya dosha, sarpa dosha and vish kanya dosha.
2. I have not yet got my kundli made. My parents also don't have a belief in Astrology.
3. I would advise you to take the kundli of the concerned girl, meet a top-level Astrologer of your city, take his/her advice, purchase stone rings or some other remedial measures and everything will be alright in due course of time.
4. But you have to find a good Astrologer who knows the subject very well.
"If you are killed in action, you go to Heaven. If you win, you rule this Earth (as beautiful as Heaven). That is why, O son of Kunti, take a firm resolve and fight!"-- Shrimad Bhagwad Gita