MONTHLY FEES CHARGED FOR NOTHING

I had a credit card with discovery which I was paying off monthly prior to them becoming a banking institute. When they requested my biometrics and I declined they stated there would be no renewal of card and I was happy. I have since paid up the outstanding and have not had any active card for this account however I still am being charged R100 a month for an account which I have no card for therefore no transactions and was told when card expires that would be it. So what is the R100 for, this is absolute *****!!