Poor service

December I got a sms from mtn stating my account is in arrears so I called the customer care and they advised me that I didn't pay the account in February 2020 so I sent the the proof of payment and they advised that there is an error on their side. January I got an sms again stating that my account is in arrears again I called them and they told me the same thing about February 2020 payment again I sent proof of payment and they said they will sort it out, February the same thing happened and yesterday the same once again. Will I have to send proof of payment for February 2020 for the rest of my life. Very poor service