Default [HELP] Urgent help required

dear all,

I have MMX A110 and i was using BSNL 3G from last 6 months via Sim Slot 1.
But last Sunday suddenly 3G stopped working firstly i thought it was network problem.
But when i put that sim to another phone and data card it was working fine.
Then i switched off 2G then everything working correctly fine.
So i shown it to service center and they said initially that phone is fine.
But problem is still there so is any one there who can help me.
I tried everything.