MFC *****ing my money

I've recently had my car financed by MFC Nedbank and they debited my account twice. On the 27th and then the 28th. I've brought it to the attention of the company but they are not responding to me nor calling me back as requested. I've sent them the banking documents but to no avail. This is such a huge knock on my finances as it's affecting other debit orders now. I'm very disappointed in them.