Surname Change In Degree After Marriage

I changed my surname from Tripti Sharma to Tripti Singh after marriage. I have given the same in newspapers and got an attestation for the same by Magistrate. I have given the same for Gazette publication Delhi for which the publish of name is in process. I want to give medical pg exam. I have changed my surname in photo id proofs and in MBBS registration certificate too after showing marriage certificate and want to change name in my MBBS degree because to give exam they say fill your name as per your degree and bring photo id proof and registration certificate with same name. When I went to university to change my surname in MBBS degree (pass out 2012) they say get your surname changed in 10th certificate first. I passed 10th in 2005 and now CBSE officials say its more than 15yrs since you passed your 10th it cannot be changed. Kindly guide how to change surame in degree as without it I will not be able to pursue further studies