Credit Card payment made -no goods

I visited Dis-chem on Monday afternoon, and selected purchases. At the till-point, my credit card was accepted and the amount was rung up. I received immediate confirmation via my cellphone that the funds had been deducted from my account. The cashier refused to hand over the goods, as she stated that their system was off-line, so no payment was made. I requested to see the supervisor. Ms Blignaut explained that there was nothing she could do. The store manager, Mr Freitas appeared after another wait and explained that Dis-chem had not received payment. Why does Dis-chem accept credit cards, knowing that they are offline ? Surely, I should have been informed of this prior to the transaction. It is now at my cost that I have to liaise with my bank, and ensure that I am re-funded with the amount, and bank transaction fees, phone calls etc. and inconvenience are for my cost.