MICROMAX CHEATS DURING WARRANTY PERIOD

I HAVE A MICROMAX CANVAS 2 PLUS I VISITED TO SREERAMPORE SERVICE CENTRE TO SOLVE MY HANDSET SOME PROBLEM AFTER SERVICING THE PHONE IS NOT GETTING ON??????
THEY TOLD ME TO CHANGE THE BATTERY
I DO CHANGE MY BATTERY BUT STILL THE PROBLEM NOT SOLVED
I AGAIN VISITED THE SAME SERVICE CENTRE THEY TOLD ME THAT THEY CANNOT SOLVE THE PROBLEM OF THE HANDSET.
PLEASE HELP ME WHAT TO DO??????????
WHERE TO GO????????
HOW CAN I SOLVE MY HANDSET PROBLEM?????????????
IF THE SERVICE CENTER OF THE WELL REPUTED BRAND DOES THIS!!!