Double Debit.

I was double debited by Marquis Finance for month of April. After seeing the matter not resolved, I reversed one of the two debit orders. I got a call the next day which I explained over the phone and email that I was debited twice hence I reversed one. I sent statements from the bank supporting my enquiry. I was told they would investigate and get back to me, which they did not do. I follows up and was told they can only see one debit order. Which doesn’t make sense because the bank confirms that the money went through to them. They still insist I did not make a payment: this is ******* and no one seems to care or have an explanation. I have been sure never to miss a debit order and now these ****** want to damage my credit record when I did pay.