Poor service

I went to shesha store Mall Of The North today in Polokwane today as I saw buy 1 and get 1 free. After I spent more than 1 hour fitting and looking for size of crocs for me, my husband and my kids, when we were finally done we went to the till to pay, the lady who assisted us told us that she can't do redeem the special on the items that are same price which my husband's crocs and I were both R1199. They told me one must be lower. I was surprised by that as it was first time I hear of such . I do know that the cheapest item is free but my items were same price🤷🏽♀️. So what must happen? Then I asked to see the manager, he said to us there's nothing he can do as that is the rule, he then said let me call them but I don't think he called anyone, he came back to say he can't do anything. I was in disbelief, belittled and wasted my time. Later I checked Shesha online to see if what they are saying is true but to my surprise I was actually able to purchase those crocs at buy 1 and get 1 free without a hustle. I'm wondering is SheSha Polokwane making their own because honestly such shops don't deserve to open because are trying to rip us off or what? I'm never setting my foot there and I'll tell my friends and even mall management about this. I work at Mall Of The North and such is not tolerated