Sony Ericsson — ringing tone is low

I brought cell phone from From Sony Ericsson Model no: W810I, Invoice.No: 1664, dt of purchase# 30th Mar'08 worth of Rs.9000/-. The cell phone ringing output is low and getting hanged which happened more than 2 consecutives times and show room executives took the cell phone and repaired it. And again i facing the same problem.

Now i want my cell phone to be replaced rather going again and again to show room for mending purpose !!

Rgds,
Pradeep Kumar. N
Mb.no# [protected]