Any engineering degree done through distance education may enhance your knowledge but such addition of qualification may not offer you substantial gain in terms of employment- prospects. You need to change your steps so that your qualification is recognised by your employer.
1) After the diploma, you can join an evening college so as to sustain the three year degree course offered by the institute and this will have AICTE approval and such qualification will be recognised by the employers and even by this qualification, you can persue higher studies in your selected branch.
2) You can opt for AMIE where in you can clear the papers part by part and the course can be persued in your convenient timing. By clearing Sec A and Sec B, your AMIIE degree will be treated at par with the degree offered by a recognised Enginnering - college.
3) The other option would be to take admission in the second year of four year degree course of some established engineering college where there is provision for intake of diploma holders. You will have to clear the Entrance - test conducted by them in order to secure admission.
The draw - back of this course is that you have to be a regular student of the college depriving you of chances of employment during such session.