Nokia 3120 Classic — Cheated by Nokia

i bought nokia 3120 classic on 01.08.2008 from Planet M. All of a sudden some problem came with the mobile i.e my voice was not going on the other side..probably the mike would have been faulty.
i gave the moblie for reparing on, then the process of going again and again asking for phone started they said its not done, spare parts are not available etc and after about 1 month they said phone is tempered and cannot and gurantee voided.
phone is not al all tempered it works fine except mike and they kept it for month and then said its tempered, phone never fell nor liquidated i think they dont have spares so they declared it tempered.i am student i bought it from my hardly saved pocket money and looking forward to get replacement from nokia
kindly help me out

Regards,
mohit kanotra
A4c-148
janak puri
New Delhi -110058
ph : [protected]
PHONE model : nokia 3120 classic
my imei :[protected]