Unable to give cashback within time period

Sir, i bought a hp laptop from tata chroma infinite store,mount road chennai. There was an offer of 5%cash back paying through sbi debit card which has to be credited in my acc. Upto 31 dec. Bt upto now there is no information about cash back even customer care is same..they are stating that we consulted with u .on 1/1/16 bt my sim is closed from last 2 month..sir, if warrentey period is over after one day they do not check items under warrentty. Then hw they can ask people to wait for more days for getting cash back
..i want full money nd allsso..with alloWance..
BILL NO-SLF02A034010071849
DATE OF PURCHASE-21-10-15
MoBILE NO of customer-8678978955