Harassment from Nedbank Home Loans on Up-to-Date Account

For the past few months have been harassed by Nedbank home loan for a home loan account which is up to date. With each call I ask the agent whether an amount is outstanding, and there is a confirmation the account is up to date. Worse Nedbank Home Loans decided at one stage to move my debit date to the 20th of each month, despite previously indicating that is one the my chosen debit dates. Thus, the debit was not honoured, but another run was done and paid. I feel harassed by them; if it's not a call, it's a letter indicating I must call to make arrangements. Worse, when calling through their call centre, you are put through 4-5 people before you get the assistance you need. Can Nedbank Home Loan look into the process as this really bad customer experience.