Wrongfully charged

<p>I have bought three unlined sheer taped curtains in the past month. The shelf displays 99.99. On the 30/05/2016 I bought another one and now I open It I see I have been wrongfully charged an extra 30 rand. The price code here clearly states 99.99 yet on my slip I have been charged 129.99, and to think that to add insult they have made an extra 90 rand out of me for nothing as I no longer have the slip to prove the other three curtains should have been the same. I do however have my slip for this and will get my money back. How can they just stick another amount over the sticker for exact same thing but a larger amount. </p>