Bad customer service

My mom went into Pep in Long beach mall to buy a modem that was advertised in the window for R599 at the till the staff member Crystal scanned the item and it scanned @R699 she told my mom that is the price of the modem is R699 not R599 my mom said to her but it's advertised for R599 and she said to my mom (the customer) that she is ***** (a ***** ) for wanting to buy it for (THE ADVERTISING PRICE )R599 HOW THE HELL DOES A STAFF MEMBER GET OFF TELLING THE CUSTOMER THAT SHE IS ***** (*****) FOR WANTING TO BUY THE ITEM THE STORE IS ADVERTISING IT FOR .JUST BECAUSE THEY DID NOT DO THEIR JOBS BY CHANGING THE PRICES .THE CUSTOMER IS SUPPOSED TO PAY THE PRICE THAT IT IS ADVERTISED FOR .I WILL NOT TOLERATE THIS TYPE OF BEHAVIOUR FROM YOUR STAFF MEMEBERS IF SHE DOES NOT KNOW HOW TO DEAL WITH CUSTOMERS SHE SHOULD NOT BE WORKING IN THAT STORE THIS IS UNEXCEPTABLE SHE NEEDS TO BE FIRED. PEP IS THIS THE CALIBRE OF PEOPLE U EMPLOY ?THEN U DON'T DESERVE ANYONE'S BUSINESS AND I WILL MAKE THIS GO VIRAL TO THE CORE .MY MOM WAS SO EMBARRASSED AND HUMILIATED BY CRYSTAL THAT SHE LEFT THE MALL IN A STATE FOR WHAT THIS GIRL DID INFRONT OF THE STAFF AND CUSTOMERS .IM UTTERLY DISGUSTED BY THIS TYPE OF SERVICE THAT PEP GIVES , HOW MANY CUSTOMERS MUST GO THROUGH THIS TYPE OF BEHAVIOUR FROM YOUR STAFF THAT IS NEVER REPORTED .