Incorrect pricing on specials

So, yesterday I crossed over to the other side.......of the Umgeni River and I went shopping at Pick & Pay Hyper by the sea. Wanted to see the upgraded shop for myself. The shop itself is lovely but slightly deurmekaar, things placed in the same isle that just does not make any sense. I did my monthly shopping, so had a rather full trolley, totalling R 1858 and some cents. Some little voice told me its a bit much, but as I had my 83 year old mom in a wheelchair with me, we loaded the shopping and went home. So this morning I study my tillslip. The special loo paper, buy 2 9-packs for R 70, cost me R 107.98. Why would I take 2 if not for the special?? Kreepy pipes, any 4 for R100. Uhm....no....I was charged R139.96 ie R34.99 each. I only needed 2, but bought 4 because of the saving. Yogurt 6 packs. Buy 2 for R26. Once again, nope. R13.99 for one and R 16.49 for the other. The special on the shelf did say ANY 6 pack......Now I am using a fine comb to go through the list. I took my own bags, but requested 1 as mine were not enough. I was charged for 4!! It seems like they are set to cheat you as many times as possible. Now they will probably request my slip and me to go back for a refund. Will they pay for my petrol and time too??? Or shall I just send the cheats an invoice??