Different store,
I was in a Lowe's buying tile for a bathroom re-model. The sales clerk rang up 1 tile and that is it. I had several boxes of tile. I told her & showed her that there were several per box, etc. She did not understand, I finally went to the service desk tried to explain it to them. After literally arguing with them (Trying to pay) I just took my reciept for the 1 tile and left.
AFTER THAT EXPERIENCE: I give the store one chance, I state clearly the mistake and if they don't fix it, don't understand, etc....... I WIN and I dont feel bad about it!