If an MTN shop says they cannot fix an MTN problem caused by MTN, what must I the customer do?

I am beyond angry with the MTN at Southgate mall shop number L111 because for the fourth time time since the second of February 2018. I pay my account every month on time and this time because of some unbeknown reason to me my payment wasnt processed, and have been harassed and my phone and WiFi blocked four times already this month. The first time I cane to the shop they told me that their system is still new and its a problem that they have and will fix it for me, they unblocked my phone and WiFi and I went home.

Got other texts for the second time saying my phone will be blocked, and indeed after two days it was blocked again. Went back to the same MTN and this time they were having a stock take and closed the shop early, and delegated their responsibilities to another shop in the same mall. When I got to that shop, they told me that it is not the fault of MTN but of that other particular shop, and most of the staff were really rude to me told me that I must go back to the other shop, but then they reactivated my devices again and assured me that the phone will not be suspended again so I went home and expected that I will not have the same problem.

27th February 2018 I get the third message that my devices will be suspended, and I almost fall off my chair because yet again I need to go to the very same shop for the very same issue like a crazy person.

On the 28th I went to the shop fuming because I cannot be coming to mtn everyday. The amount of time, patience, and money in coming here every other day has been immeasurable. Not just that but when I get to the shop I get highly arrogant gentlemen who I feel have been incredibly rude to me as a loyal paying customer.

Today the 1st of March 2018, I woke up, and my phone was suspended yet again. At this point I am disheartened because I would have assumed that I would have been treated as a priority the first time I came to shop. I am very busy and use my cellphone and WiFi device constantly for my work and school purposes. I have been highly inconvenienced throughout the month, and now need time lines from mtn of when this issue will be resolved, and how my time money and energy can be replaced because at this point I don't know what else too do.

I have all relevant texts, payment slips and reference numbers, which have just piled up thus far.

I need an urgent response ASAP.