Pathetic service from MTN

I am struggling with my account since Nov 2020. Mtn moved to a new system and my payments since Aug 2020 does not reflect on my new account number although they refer to the old account nr on the new invoice. I wanted to upgrade in Nov 2020 but had to pay a cash amount as my account showed it was in arrears. I paid but supp**** the proof of payments since Aug 2020. Phoned in Dec 2020 to follow up but nothing was done. Resend all the proof of payments to 2 email addresses. Phoned end of Dec and was told everthing is allocated and I am in credit and did not need to pay Dec. Phoned in Jan 21 as I got an sms that I was in arrears. According to them no payments was allocated and I have to resend AGAIN all proof of payments. This is incompetence at a high grade.I can upgrade again on two lines but think with this kind of service I should consider moving to a new provider.Not happy with MTN service at all.Ref nrs are ***, ***, ***, ***, ***, ***, ***, ***,***,***, ***.