Pathetic service once again

I was at 1 of your food retail stores, i purchased 5 items and on checkout i optes to use my woolworths card but to surprise my purchase wouldnt go thro. Bearin in mind my credit available was R12000 . So the cashier says mayw because i haven't paid my installment. It the 24th, my salary was not even paid to me so so how am i supposes to pay an installment for u to refuse any purchase. Most embarrassing situtaio .Never again woolworths!!!!