Problem with contract

Good day, a while back we had a problem with a OBF phone that we got on contract, we received a new phone 20 days after the OBF was sent in, I complained as my services was suspended, the person from headoffice contacted me and said they will pass a credit note because I didn't use the phone so I don't have to pay, just have to pay for the airtime. This week I wanted to make a payment of the outstanding, just to see the credit has not been passed yet so they wont be able to turn on my cellular service. Also another thing we received a credit note for the OBF phone, yet they want to bill me for it, they extended my contract from the signed 24 months to 51 months making the phone R23000 (CAT B15Q), so with that said they want to charge me for the OBF phone and the replacement one. How many times must I write a report here just to correct things before it gets corrected? if I phone headoffice directly I get a lady with an attitude that thinks im lying when I try to tell her when we sent the phone in and that the credit note headoffice told me about was never passed. Im done with struggling, we still cant use the phone at the moment. Please let me know when this will be fixed properly.