Erroneous Double debit - CANT GET HOLD OF ANYONE!

Last month I had missed a DO , made an arrangement to pay when I can or a double debit the following month (26th Oct)

However ! I had managed to pay via eft , and upon calling to confirm , was told that only one installment would be going through.

Wham Bam I wake up to notifications that MFC / Nedbank did indeed double debit , and I cant get hold of anyone via phone , and no one is responsing to any of my emails.

I need the overpayment to be returned to me immediately ! I have othe financial obligations that need to be covered , so telling me you will credit my account is just not good enough !

CAN SOMEONE PLEASE GET HOLD OF ME ASAP !