Billing

I have a ackermans account which is paid by debit order every month and is always up to date however I went into ackermans south gate and was embarrassed to find that when doing a purchase my purchase was declined and my card block as if I was someone who does not pay my debt .The cashier Patricia was very unhelpful and rude and gave attitude advising me that it is not her problem and when I asked her to call there head office so that I can find out what the problem was she acted as if annoying her .The service was really dissapionting and I still don't know the reason why the account is blocked.