Trying to ***** from there customers

I just received an SMS from them that they are going to hand me over for outstanding amount, they have been debiting my Mercantile account since last year September, now I find out they have been trying to debit from my old FNB account also. This is low !!!!! Phoning there accounts you are sent from one person to another, then they wanted me to sent trough my account details again so that they can do a debit order for the "outstanding" money.I told her they are nuts for asking me to pay for an account that is NOT in arrears.