Dell — Cheated by Dell

I have bought a TAB Dell venue 7 3741 on 13 june 2015 from rohini and within few days i have started facing issues in the product .I have visited the authorised service centre of the company 3-4 times where every time i was told that the issue has been resolved by them but nothing happened and the issue was still continued, after getting tired of visitng the service centre, i have called on the compalint/customer support no to register a complaint basis on which i have got the mail on 24th jul from the company that they will replace my TAB and they wanted me to submit my old TAB back first which i did (copy atatched for the same).Even after writing numerous mails and doing various call si was only getting the rely to wait for some more time with one or other reason, finalyy after more than even a month i have got the call from courier company that they have received the TAB from dell and inspite of delievering it at my address they have asked me to come and collect it from their office, i even did that post reaching there i have been told only TAB has been sent by the company even the charger was not sent however the old charger was returned by us any ways we accepted that even but within a day i have realised that the issue is still the same and even have a doubt that i have been given the same tab back as i am still facing the same issue for which i have lodged the complaint 1 and half month back. I am feeling cheated and harrassed by the company as my money is swallowed by them by providing a faulty product with fake resoltuions and committments. i have got a major setback as it was gifted by me to my sister and i have lost my goodwill due to this faulty product . I need my money back with a formal apology letter on on the letterhead failing which i will file a legal case against the company