Longest Sim Swap of my Life and I'm Paying for nothing

If There was a rating of Zero I'd put zero rating. I know I'm a former employee of MTN and I have been quite reserved with my frustration because they perceive complaints from former employees as malicious and bitter. My situation is that I have been trying to do a sim swap for my contract number for almost two years now (at least 15 Months). I tried Greenacres MTN, Cape road MTN, Mthatha Bt Ngebs MTN. I Filled the sim swap form and PAID the sim swap amount, but the sim swap does not go through and I was told that the number needs to be Migrated. A USD request was lodged, every time they actually respond they always say the reason that my sim swap doesn't go through is because I'm owing (only because I'm tired of paying for services that I don't receive at all). When I pay the outstanding amount, they tell me that the sim card needs to be migrated, and I waited months but migration is not happening. When I lodge another complaint they say I'm owing again. Imagine I'm paying around R2700 every month on this account (it's been 5yrs now) and they told me they can't do the sim swap coz I had an outstanding balance of about R300. I'm so tired of this up and down I don't even know who to talk to, I feel helpless