BAD AFTER SALE SERVICE

Blackberry Z30 9 months old stopped recognising the SIM card. Took it in on 7 July for repairs. Got no feedback until I contacted the call centre on 1 Sep. They rep**** that the quote was rejected(a qoute I never got!) And I have to pay to get my phoneback unrepaired. They claimed that the screen was cracked and the phone was abused. The lady at the branch phoned them and stated that my phone was as if out of the box with no scrathes even. After emailing back and forth I received an email stating that my request was escalated. This was on 4 September. I received no communication since then. I am very upset and feel that this damage to my phone was caused by the technicians who worked on my phone in April when the screen was replaced after it did not display anything. This phone is still under warranty and I want MTN to replace it with a new phone. I am with MTN for more than 15 years on this contract and expect better service than what I got. I am awaiting your speedy response.