MTN has NO customer service. Dragged my credit history in the mud now.

So in 2019 on the 9th of December i paid my Mtn contract IN full! Well this is the second review on the same problem. Now a year later they have flagged me for not paying my account after paying the account in FULL. I am now in the UK. I am FURIOUS... i have an amazing credit history. I am now *****ed thank you to MTN for flagging me for not paying its NOT on.