UPGRADE DONE,NO PHONE,NO RELY-JUST BAD SERVICE

My dad did an upgrade on his cell phone on the 12th of January 2016, Ntombana said to him that he must cut his sim card so that it could fit his new phone (Samsung Galaxy A3), I thought this was a strange request as normally the store would supply a new sim card (which I understand at the time they did not have stock of the sim card).We cut the sim card & tried to get it to work without success. We took the phone back within 7 days but they refused to give us a replacement phone saying that we damaged the phone (note that this was at their suggestion that we cut the sim card).We wanted to cancel the agreement but they said the phone is damaged. They then suggested that they send the phone in for repairs perhaps it was under warranty which they did and we got quick feedback, they advised that the guarantee would not cover it and suggested that we send it in for repairs. That was 2 - 3 weeks ago and no reply. I have called the store around 8 times but it is either Ntombana is off and I must call the next day, or if i get hold of Ntombana she said she called the service department and they don't answer.No one takes responsibility and nothing being done and no cell phone a month later.