MTN Nicolway Shopping Centre, disgusting service!!

My wife took out a new contract in December 2019 for an iPhone 7 Plus from the MTN store at Nicolway, Bryanston. The phone never worked properly from day 1, no-one could hear my wife, sounded like she was under water. My wife took the phone back and it was sent in for repairs. Phone came back saying no fault was found. Again, every call no-one could hear my wife. Took the phone back again and same result, no fault found. My wife then phoned the manager there, Porche, and guess what, Porche could not hear my wife. Took the phone back again, and that was beginning of March. It is now 5 July and MTN Nicolway still has the phone with no resolution. Porche never returns calls and when my wife did eventually speak to her, she said they may be able to offer an iPhone 7, but my wife must now pay in for that. If my wife has a problem with that, then she must write a letter of grievance and they will consider it. I went to Centre management at Nicolway and they passed on a message to the owner of the store as it's a franchise, and he has never called me back, does not care at all. So a brand new contract which is not being honored with a brand new phone and 7 months later my wife still does not have a phone, all the time paying for it. Absolute shocking service and no resolution in sight, disgusting!!