MTN HAS DISGUSTING SERVICE

So its been close to three weeks and as yet MTN has not sorted my issue out. I have posted 3 times to HelloPeter and have sent 4 emails to [Email Removed] NOT A SINGLE RESPONSE! I upgraded my contract a moth ago. Since the upgrade, I have been unable to receive calls on the handset (Galaxy s6 Edge plus) I contacted MTN coverage and Samsung South Africa. Samsung informed me that the network must have issues because the handsets all work. I took the handset back and replaced it. I tested it at the branch and it worked. Took it home and since being in Farrramere the handset does not receive calls when on LTE. I called the coverage department and the service agent told me the phone was working. I told her I don't receive calls. he blatantly said that I do and hung up on me. I am still unable to receive calls and have since moved to Vodacom. I would like to close that contract and return the handset. I am disgusted with the level of service. MTN is indicative of what to expect in the future. MTN is in breach of contract as I am unable to utilise the network that I pay a lot of money on! The same contract that was upgraded still has not received its data. MTN is pathetic.