Mtn
Faulty phone

I have a contract with MTN i bought a blacberry 9360 last year June. It became faulty last month and it was booked for repairs by MTN Northgate mall, on Friday they called me to go fetch it to my suprise i was told that it was not fixed - it can't be fixed, when i read the report from the Allandale repairs, it say BER -
its not my fault that the phone is faulty - How can I pay for the phone that i don't have that i didn't damage, that has been written off by MTN.
Is MTN not supposed to give me the new phone