Consumer Redressal

We had purchased a Lenovo B300 AIO computer from the Reliance Digital store in J.P.Nagar 2nd Phase, Bangalore. 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. But 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 more than 10 requests, there has been no response or any action from Reliance Digital to cater to my request. Is getting a duplicate receipt such a huge task or is it too much to expect a duplicate receipt from Reliance Digital?