Tata Sky — Set top box defect

Address:

400071

4 months back I was told that my set top box is not functioning and I should replace it at a charge of rs. 700 ..having done that, Today I am facing the same issue and don't think it's fare by the company to keep charging me gain and gain .. I have already changed the device twice.. I have tried speaking to customer care cell but aren't able to provide any support on this .. I am writing this anticipation of a positive response ..