Consumer Redressal

We had purchased a Lenovo B300 AIO computer from the Reliance Digital store in J.P.Nagar 2nd Phase, Bangalore on 17-12-2010. The computer developed problems within 17 months and ceased to work. After constant persuasion with Lenovo for about 9 months, Lenovo has agreed to compensate us the full cost of the computer. For this they need the receipt/invoice provided by Reliance Store when we brought the product. The original receipt has faded beyond recognition and hence requested Reliance Digital to provide a duplicate copy of the receipt. The billing team at the store says they can only see old bills on their network but cannot take a print-out or email the same. I approached their customer service team and registered my grievance. But even after 10 days and 10+ requests, there has been no response or action to cater to my request from Reliance Digital team. Is getting a duplicate receipt such a huge task or is it too much to expect a duplicate bill for the purchased product?