Double Debit without sufficient explanation

I was double-debited for December. I am calling to get answers and I am being sent from pillar to post. I was sent to 4 different departments(Collection, Refunds, Accounts, Client Services), and none of them can give me answers.

The error was on the side of MFC and I am now being told I have to wait 5 to 7 working days before I can be refunded, and what they are failing to understand is that is not only about the refund, what about the financial impact that this has caused on my end, I now have to pay penalties for failed debit orders and this also has a bearing on credit status with my bank.

This has had a huge financial impact on my end because it means I am not able to meet my financial obligations with other institutions.

Why am I the one to bear the brunt of the error that MFC made, I need answers here.