MTN Low quality service!!

I’m very disappointed with the low quality service I’ve been receiving from MTN I called in multiple times with regards to my contract and the incorrect information on my billing account, spoke to different agents saying that they have cancelled the incorrect information yet I’m sitting with the same problem I went to two different MTN stores in Southgate and Trade Route yet I’m still sitting with the same problem to a point whereby it’s starting to affect my credit score , MTN is Double charging me for one device ( Debt order and cash payment in store) after going to rectify their mistake , nothing changed until today I’m sitting with a big problem!