MTN and their useless service to me

I have been a contract customer with MTN as from 2000. I have never had any trouble with them and pay my account via debit order religiously each and every month. However, I upgraded in May and since then I have had nothing but trouble with them. For the first time ever - without informing me - that put a limit on my account. I thus had a smart phone that was not al all smart as I could not use whats up, internet or any of their other services. I mailed their customer service and called them on their 808 number. They informed me at the call centre that I only have a limit of R150 therefore my service has been cut. I asked them to up or remove it. They managed to up it with 1 cent only. I complained again and they managed to uplift it to R1350. But then it happens again this month! No service! I ohoned their 808 number and they promised it would be ficxed within an hour. That was Monday 13th. It is now Monday the 20th and still nothing. I mailed them and used their sms service (44303) still no reply except I should go to their self help service. I tried to register only to find that they say my phone does not belong to me. I mailed them with the proof only to get an answer phone 808