worst service

Location/place: uttam nagar new delhi

Name of company/service: nokia

I have purchased nokia-5130c from mobile shop on 14 aug 2009. it got software problem within warranty period. I submitted my phone on 29 july 2010 at Ace Communication(Nokia Care Center), kapil vihar, pitampura, new delhi. they repair it but after 2-3 days auto-off and display problem occur. i submitted my phone again on 3 august2010 but after getting it repaired problem remains same. i again go there next day. they just checked it and said that handset has no problem. but problem is there. i again went there on 10 august 2010 and my phone is submitted there.they said me they will forward it to head office. but on 12 august 2010 they return it to me saying that problem is resolved but i think they returned it without even seeing the problem.as problem of white display during call is there. 0n 14 august 2010 i went there again as it is last day of my warranty. but they refused to submit the phone. and they returned my phone after 1 hour after checking and said u will not get any problem but problem is there.kindly see in my problem and their delaying has ended my phone warranty. kindly help me out in replacing my hand set.