Non-payment of refund

I cleared my Makro loan account, but their statements only go out in the middle of a month. Upon receiving the statement, I realized I overpaid my account. Now it is an endless struggle to get my credit amount back and I am left having to pay for admin charges (monthly services) due to the account being in a credit balance. When I phone Makro everytime, they say I must wait 7 to 14 days. For them only to get their admin monthly charges. I am fed up having to struggle with this as I am a good customer for many many years!