poor customer service

I bought books from checkers hyper parklands. The books was advertised for R9.99 A4 hardcover 192 page when I got to the till the books scanned R15.99. the cashier called the supervisor Lindiwe Hlehla to change the price she then called the manager Renier Boucher who made such a scene and told me Daar is geen manier hoe ek dit vir jou gaan gee vir R9.99 nie jy kan my maar op hello peter report ek gee nie om nie. I felt so humiliated the cashier Mabore Moshia was laughing as if im the stupid. its not the first time they advertise something and you pay a different price for it. the supervisor said something else was marked for R9.99 not he H/cover books, but the poster cleary stated A4 H/cover books