Sony Ericsson K790i — Refusal of Mobile Replacement even after repeated Complaints

I bought a Sony Ericsson K790i mobile on 31/08/2008 and it suffered from hanging problem since the very first day. Even after Master reset and updating the phone software it still suffered from the same problem.

So I submitted it to Technocare Services, Lajpat Nagar which is the Authorized Sony Ericsson service center. The returned the mobile after 3 days and the very next day the phone was hanging after every 1 hour and the battery had to be removed. After putting up with this nuisance for a month I submitted the handset again to Technocare. After saying that they have replaced Motherboard etc . they returned the handset after 10 days and again it was hanging immediately.

Finally I submitted then the handset for replacement but they again returned it saying that they had replaced some parts and again the same problem. Today I got it repaired for the fourth time and I have no hope that it will work.

Now even the IMEI number on phone back panel and the one displayed on screen do not match.

Please suggest how to bypass the dishonest people at Technocare and contact the company directly to get my phone replaced ??