Poor Mtn customer service

I have had a contract with mtn for about +_ 6 years and for the first time I am extremely frustrated with the poor customer service I have been receiving. for the past 3 months my phone has been blocked by mtn more than 4 times a month, each time I call a consultant I am informed about an outstanding amount of R661,00 for the month of July 2020, each time I call I am given the same feedback and clearly 3 months later from mtns side the matter has still not be resolved even though I was requested to send proof of payment which I did and today yet again my number has been blocked. What frustrates me even more is that I informed each consultant I have spoken to that I am working from home and need to use my phone, today I find myself in the same situation which I have been encountering for the past three months, all my time and effort to resolve this matter has been taken for granted and I am receiving no assistance from mtn at all. I have always spoken highly of mtn but now my view has changed, I very disappointed in the service I am receiving and considering cancelling my contract when it is due for an upgrade.