not refund my money

Oder purchase date 13/3/2015 My First Complaint No – QRC231709 Second Complaint No – QRC3346899 Third Complaint No – QRC402784 I received the product MI Power Bank Rs.699 but it was not original . Raised it for return, they picked up the product but till date no refund. When i call Customer care says it will refund within 10 to 12 working days. but till now not happening. Nearly two months over.whenever i am calling they telling same story it will under process within 10 to 12 working day amount will refund like that.i given my bank details but no use amount not credited still now. today is 13/5/2015 please help and refund my money my no 9990884496