MFC at fault of not debiting the correct bank account. Take responsibility

I purchased a brand new VW polo financed through MFC. My debit order was supposed to run off my personal account, but as it turns out is that MFC decided out of their own to debit my business account. I did not authorise this and nor did I give any instruction to debit the business account. My clear instruction at the point of signing the contract was that my personal account would be debited. Now I phoned MFC to try and correct the situation, but apparently, they can't do anything as I now need to deal with a collection agency. Firstly, this is not my fault. MFC needs to correct the situation and retract and correct any kind of negative comments or negative impact on my credit profile immediately. I trust that this matter will be resolved ASAP and that my credit profile will not be negatively affected.