Treated like an idiot

I visited my local Ackermans today, I found shoes for my kids on Sale. Take note I took 2 pairs of the exact same shoe in a size 13 and size 12 exactly the same barcode and from the shelf clearly marked in bold red letters as SALE. I also took a pair of shoes exactly the same as the others in black and for boys from the same shel****ain clearly marked SALE. Only one pair of the shoes had a res price tag stuck on it. Got to the till point as low and behold the black boys shoes was not on sale - ok fine I can live with that (decided to take the shoes in any case) Next the pink pair of exactly the same shoes - the pair with the red tag was at the sales price but the other pair not. When I queried how that is possible I was told well there is no red price tag on it so its not on sale. I asked the sales lady to explain as it was the exact same shoe with the exact same barcode from the exact same SALE shelf. I was told that it is not her problem and that is just the way is is - no red tag no sale. I even phoned their customer sales department just to be told that if it is the way the store policy is I can't ask for the cheaper price. During all off this I was treated as if I am an idiot and looked at like I am being difficult for no reason. The sales lady sighed and rolled her eyes as if I bored her. I have been a loyal Ackermans customer for many year and is upset at not only at the bad customer service but the fact that no employee even made an effort to find out if there might be something wrong on their shelf or their tags. I would really like to know how the same product on the same shelf with the same barcode can differ in price.