Problem in Blackberry Phone

Location/place: Noida

Name of company/service: Blackberry

I bought a blackberry 8520 phone in Sept 2011 with 18 months warranty IMEI 357257047344978.In Aug 2012 there is problem in my phone the mute & unlock button broked down,I gave the same in service station,after 8 days they call me & said that there is some other problem(I do’t know what) occured in my phone which is not covered under warranty & that why they’ll not touch my phone for repairing.

Please confirm then what does warranty means incase you cannot sort out my simple issue.
Pls look into the matter.`

Regards
Abhishek Rajput
9312293766
[email protected]