Super disgusted in service

a contract was taken out with MTN in 2012.<br> Contract ended in May 2014. In september 2014 MTN blacklisted the wrong phone.Have been phoning and filling in forms even got an affidavit for MTN. have been in contact with three people and now they tell me the phone is ******* as there was an insurance claim on the phone as if the phone was ****** and now i must phone MTN to convince them that i never claimed for the phone. and i asked if they have documents to prove that a claim was put in and they say no everything was done on the computer, i mean surely you must sign for insurance claims. What must i do now run to the papers for this to be resolved. I have been without a phone for 6 months and no one can help me. this is really unacceptable.