FNB latest ****

I've phoned this bank as a private client account holder more than once. I use my card to make purchases after which I get an FNB notification telling me that the money has been deducted from my available balance. After a few days this same amount gets deducted again for the same purchase not from pending or reserved funds but from available funds. Thus they use my available funds to pay for purchases which was already reserved for the same purchase. When you phone them they keep going on about the merchant this and that but does not do a thing other than sending you a dispute form which in its own does not allow me via any of the options to dispute what happened. In other word FNB has started *****ing from me and don't understand what they are doing or how their own system works.