GTX470

I am facing the same problem for a year now. I have changed by sim card twice asking for Diamond OMH card. Number remained the same. I have a Samsung Y i509 CDMA handset. However if I change the sim with my colleague's sim (checked with 3 different simcards) then internet works. I also have a monthly 1GB plan for Rs 125/- that I am paying but cannot use. I have made upteenth visits to Reliance world stores but they are clueless. Quality of Customer service is pathetic. What are my options......? Any solution....? appreciate speedy resolution if possible.