NOKIA E-71
Set not working properly

I purchased Nokia hand set E71 (3G), bearing Ime no 354855025241661, initialy phone starts displaying connection error at the time of calling and sometimes displays insert sim whereas the sim is already there and other fault is that the phone goes to switch off mode on its own. The battery backup is very low. The phone heats up to an abnormal temp. Going to the service centre EMM ARR COMPUTERS BAKSHI NAGAR JAMMU, instead of solving my problem they created another problem by deleting data stored in memory card, Sim and Phone itself. Phone was returned within 5 mins of the complaint, stating that all "Faults repaired" and therefore job card shall not be issued. Kindly help me and tell me wat i should do.