Paying for faulty phone

I upgraded my line a couple of weeks ago and MTN sent me a faulty phone which I took back to the South Gate store for repairs, I received an sms that the phone is ready for collection however when I got to the store the consultants says the phone is not there, when I try to call the call Center I am transferred to 1000 departments and no one can help me, does this mean I need to pay for a device I don’t even have ?