Poor service and wrong debit orders taken off

I've had my car for a few months now and haven't had any issues with my debit orders, this month I cancelled my warranty and I had a refund sent to Volkswagen Financial Services as I know it doesn't come back to me but will be sent as an Advanced amount on my account.

This month I received my invoice stating how much would come off my account (R928.43). Which was my full amount R3240.60 but my refund had been deducted, so it came to R928.43.

But this morning I had the full R3240.60 deducted.

When I phoned to follow up and see what exactly happened, the lady I spoke to (Michele) said I had missed a payment a month or 2 ago and this is why a full deduction was done because I was in Arrears.

Which is total ******* as I know every month my debit order has gone off. When I started explaining my side of the story with the refund she started shouting at me saying that I was incorrect and I owed them money.

Perhaps I am in the wrong but my invoice showed a certain amount to be deducted but they took another amount? This is quite frustrating!