Over Charged

I just got back from the checkers in pineslopes. i was over charged on the items that i purchased!!! the store price and the price i paid differs. for example the nestle choclates that are on special 3 pkts for R90, i paid R38.99 each. the yum yum was on special for R47 i paid R58.99. there are more items on my list that i was over charged for. this is ridiculous. i would like to know how this is going to be resolved, i have kept my till slip.