MTN refuse to give us a copy of the contract

My husband bought a phone (Sony E4) from Lydenburg MTN in August 2015. The phone was faulty and subsequently sent to Midrand Repair center for repairs. MTN repair centre advised that the store is required to give us a new one as it was factory fault. After a 2 week period of Lydenburg MTN telling us the phone has been ordered without giving the concrete date as to when it will be delivered, they eventually advised that the model is no longer being produced and that their operations manager in Johannesburg has approved that they will give us a Sony E4g. The Manager at MTN Lydenburg Joseph, said that we need to bring R150 with us when collecting the phone. My husband refused to give the R150 as we did not understand why MTN wanted to charge us for a fault that was made by the manufacturer. Joseph gave him the phone without signing any documents nor giving back the copy of the contract. Now we are experiencing problems with the E4g phone as well, we need the copy of the contract for repairs. Joseph refused to give us a copy of the contract without paying the R150