Sale not going through

I AM COMPLAINING AS THE VERY SAME INCIDENT HAPPENED PREVIOUSLY. I GET A MONTHLY STATEMENT AND I CHECK MY CREDIT AVAILABLE ALL THE TIME. I ALSO PAY DOUBLE MY INSTALMENT EVERY MONTH SO I DEFINITELY KNOW THAT I HAVE CREDIT AVAILABLE TO PURCHASE SOMETHING. I PROCEEDED TO THE TILL TO PAY FOR MY GARMENTS AND THE CASHIER TELLS ME IN AN ABRUPT TONE YOU NEED TO PAY R12-00 YOUR ACCOUNT IS IN ARREARS. I THEN PROCEED TO SAY THAT I AM CERTAIN I HAVE ENOUGH CREDIT. HE THEN LOOKS AT ME IN A RUDE WAY AND SAYS YOU NEED TO PAY R 12 -00. I THEN CANCELLED THE TRANSACTION AND SPOKE TO THE MANAGER. I ASKED THE MANAGER WHY THE SYSTEM IS NOT UPDATING MY ACCOUNT, HE DID NOT EVEN APOLOGISE BUT IN A NASTY WAY SAID THAT I MUST PHONE THE ACCOUNTS DEPT TO SORT OUT AND JUST WALKED AWAY. IS IT MY JOB TO DO THIS? SHOULD I PHONE MR PRICE ACCOUNTS EVERY MONTH TO UPDATE MY ACCOUNT. SURELY A BIG GROUP LIKE MR PRICE HAVE ENOUGH STAFF TO OVERSEE CUSTOMERS ACCOUNTS. I AM A LOYAL CUSTOMER WHO PAYS MY INSTALLMENTS ON TIME AND I WILL DEFINITELY CLOSE MY ACCOUNT WITH THE PATHETIC SERVICE THAT MR PRICE DELIVERS.