Taking money from my account and not refunding

I had loans with Getbucks and settled ALL of them. In fact, an amount of R81 odd cents was OVER paid. (I have requested a refund, but am being ignored). Now I see that they again deducted R18 from my account. FOR WHAT??? Please sort this out. If you deduct R18 *******ly from 1000 people each month, you make quite a profit don't you? I mean, who makes a fuss for R18?