Online exchange of SD STB with HD STB/HD DVR

[pramitr1]

I have a SD STB. I want to now exchange it with HD STB/HD DVR.What should I go with???HD STB or HD DVR.Also there are some good exchange offers with Videocon D2H HD if purchased online coz I had purchased my SD STB by ordering it online and got extra cashback in comparison to purchasing it from local dealer.Is it possible that I can avail the exchange offer by ordering it online or is it mandatory to call CC Executive to avail Exchange offer.Coz as of now I dnt see any exchange link any any means of online purchase of HD connection would treat me as a new customer.But I want an exchange offer.Please help!!!!Also some pics of D2H HD DVR would be helpful!!