Disconnected services on a weekly basis without any assistance from MTN

We have been a client of MTN for 30 years. Our account is in arrears according to MTN. MTN can't seem to send us the invoice for the amount outstanding. They keep on disconnecting our services on a weekly basis. The closing balance on our statement of 30 April 2023 is not the same as on our opening balance for 1 May 2023. There was another invoice after the closing balance on 30 April 2023 apparently according to MTN. They can't send us the invoice. We have a business account and we are starting to experience a loss of income due to our services that are disconnected on a weekly basis. We look unprofessional and *********** and it is humiliating, even though we have sent proof of payments for invoices that was sent to us for the last 10 years. We receive absolutely no assistance from MTN regarding this matter. We have never experienced this kind of incompetence from customer services.