Not taking customers serious

hi<br> my name is Esther, yesterday morning i was shopping at Pick nPay family Denneboom store, i bought enterprise french polony 500 g at the shelve was R17.99 but when they scan it , it was R21.99 i told the cashier that this is not same price i saw at the shelve, she did not bother make means of checking if i am wrong or what she continued with other items and gave me slip. i had to leave my items at the till unattended to go and verify the price. i spoke to one guy wearing pick n pay uniform he called Ms Maluleke, she just took out the price and called me in front and give me the difference of R4,00. i asked her about the scan ride board that is hanging on the tills that states that should a customer get overcharged he/she will get two items free and the difference she responded rudely saying this thing is no more working , i then said why is till hanging there she kept quiet and leave me standing there. i wonder how may customers polony bought with that amount. i m still having the till slip their number is ***