Sony Ericsson — next day mobile is not working

Address:

Mumbai City, Maharashtra

I have purchased this mobile s-312 , Rs. 5,150/- at andheri Shop on dt.12/06/2010 and next day have a little liquide damage, now it is not working.I have given it for repair at Sony authorised servicecenter. Service center people are saying motherboard is totaly Damage that you have to pay 4500/-Rupees to get it repaired & Costomer service charges RS. 150/-
My Phone is in Warranty 1 year period
This product is having lots of problem since from the day it has been launched. Pleas give us any solution for this matter becuase handset is Rs. 5150/- & its service charges 4500/- plus Rs. 150/- its to high. what i can do legal action please tell me.