Exhausted and frustrated.

I have an MTN contract for about 10 years now, I have never experienced such bad service as I have in the past 2 months. I pay my account each and every month between the 26 and 28th. Now, I am being told that my account is in arrears with 1 payment. I have sent POPs for every month over the past year and the consultants just cannot tell me where and when I have skipped a payment. First it was June 2020, then May 2020 I was further told that November 2020 is outstanding. every time I submit the POP for said month they move over to a new month that could be outstanding. Now I sit with lines that have been suspended. I was told some story about new systems - that is not my problem. I cannot call the department I am told my call center and I am getting no joy from communicating via emails.