Overcharging constantly

I went to Makro Wonderboom for a credit on an A/C unit that they overcharged me for, promo price was R 3999.00 and I was charged R4499.00. On the day I went back to the store to get my credit I bought Saving Blades. Promo price on the shelf R 390 odd rand, Price on my slip, R 449.00. That is not all, when I was at the branch there were 3 other people in line waiting with the same complaint. I spoke to a colleague of mine, and the same happened to him at the same branch. I wonder how many people they overcharge and never get complaints about because it's just to much of a hassle to complain.

Makro, don't you think it's time to take a look at your system?