Very bad service

Last year I was granted Covid relief on my home loan for 6 months. It started in April and ended in September. I have been getting sms'es and calls to say that I am in arrears. I told them I never missed an installment. When they checked their records they found that they reconstructed my account early than they are supposed to. Reconstructed in August instead of September when my relief was ending and that created a month in arrears. They have been promising me to get this sorted as it was an error from their side but still today nothing has happened. I received an sms this morning to say my account is in arrears, this means this hasn't been resolved. This issue has created a bad name on my credit record and the last time i spoke to their agent i was told they wont be able to fix my credit record because this is automatic. I cant get any credit because of this. I want the issue to be resolved and my credit record to be fixed. Every time i call Nedbank I am told i will get confirmation, this has been going on since October last year.