Consumer Redressal

I purchased a tablet PC HCL Y2 serial no 512edr012080 on 22-11-12 from south ex.and after some days i came to know that it was a defective product. I went to service centre nehru place and they sent me to a different shop at janakpuri for replacement. i went there on 27-11-12 and got a new tab sl no. 521edr001099 which was also a defective one. When i complained to them, they told me that they dont have any other y2 tablet left with them and advise me to contact service centre for the refund process. Nither the service centre nor the dealers want to keep the defective tablet with them. Service centre gave me an email address on 28-11-12 for the refund process. Then i started sending email to the nodal officer and hcl touch service from 28-11-12 onwards but they did not bother to reply me. I have proof of all the emails that i sent to them. Its already been 25 days and i did not receive any call. Please help me to get my money back and kindly advice the procedure on how to file a case.