Bad service

i made an insurance claim as i have a contract with MTN my phone was damaged, it was collected on the 4th july for repairs and on the 11th August they returned a wrong phone which had a broken screen. So i emailed them to come and collect it immediately courier came on the 21/08 to collect the phone from me. Since then i have not received my correct phone i emailed them all the information they asked but nothing from them only calls asking for IMEI number and it was quiet, this week no one has come back to me, its going to be 2 months without my phone i dont know what to do. I asked them how can i pay for a phone that has been with them, its clear they cant find my phone i asked to be given a new phone than. No one gives me a honest answer. i am just fed up with MTN.