Double debited and Need refund to be processed

I cancelled my account with Virgin Active and was in arrears by 1 month. Consultant called to arrange payment. I gave them authorisiation to debit the outstanding amount of R770. To my surprise a total of R1540 was taken out of my account by them. I spoke to another consultant who advised that only R770 reflects on their end.

There is a mismatch and I need it rectified and balance paid back into my account.