Motorola F3 Mobile Set. — Defective Set.

I purchased one Motorola F3 phone for my wife on 01.01.2007 and within a year it went defective for twice. On each occasion I had to go to Motorola's Redington service center at Sarat Bose Road, Kolkata and they after keeping the set for more than a month handed over the set with different IMEI no. The logic from their side was that this F3 set is not repairable. On last occasion I was delivered a different set without testing and after going home it found defective again. Compelling with the situation I had to go their office on the next very day and after 1 hour they handed over a different set which was deposited to them for repairing 01 month back. If this F3 set is not repairable then how they have delivered me the same set which was defective and submitted for repairing? The clock of this set never gives the actual time as it is always goes slow. This problem was found from the very beginning and was reported each time I submitted my set for repairing, but nothing actually was done in this regard.
Being worried of recurring expenses for repairing of the set (as warranty was over), I had requested the President & General Manager-Mobile Devices (India), Motorola on 14.02.2008 and after that my set was replaced with another one which was said to be a new one. But the set is locked for IDEA Sim and as I am having BSNL connection I am unable to use this set. After that on each chasing, either by going to their service center or by sending letter, they intimate me passwords for unloacking the set and the same does not work everytime. On each ocassion I am used to be contacted by new person and receive new set of password but the problem remains the same as the password does not match. Hence the set is lying to my table as a show piece.
In this regard I would like to request for necessary action in this regard under intimation to me.