Samsung / Galaxy Smartphone — disputed handset

Address:

South 24 Parganas, West Bengal

Dear Sir,
I bought a Samsung smartphone GT-I9003 with S/L No: RV3B459288E. IMEI No: 356107/04/399703/3 on 25/06/2011 from Spice Retail Ltd. 32, D P S Road, Kolkata-33, vide Invoice no.[protected].
From that day till today i have visited 3 samsung service center accross Kolkata for repairing of the phone with the same problem of touchpad & frequent software problem. I have been assured by the respective service centres that all my problems were rectified and necessary parts were replaced, all the three times. But after every 2 months again I am facing the same problem and now the phone is not opening it just stops after showing the samsung logo. Now I am just fedup of this phone and it has also crossed the warranty now. as during warranty whenever I had deposited my phone, they keep the phone and then say after few days that all the problems have been rectified. It works fine for 2 or 3 months and then the same problem arises. Its been 4th time and now the warranty is also over and I need the replacement of the set as I claim that the above set sold to me was a disputed one.