I guess the customer really does not matter

On the 29.11.2021 my sister went into Dischem Chatsworth to make a purchase. She followed up on the Disney promotion and was advised the promotion was no longer on. Disappointed I discarded the brochure with my stickers. I went to the store I think it was the 08.12.2021 and I see the gifts are still at the information counter and I asked the lady. She said I should speak with the manager. Justin arrives and I explain him the issue. His reply was I should have confirmed with another person and should not have taken the cashiers "word" for it. I questioned if the staff informed are not trained and further more why would I doubt they information provided? When you are told sometime is R10 do you go around the rest of the store questioning staff to confirm the price?? What a ridiculous response! Justin said he would watch the video footage and I asked for a written response. I get a call from Denise today 15.12.2021 to advise that she is handling the matter...she mentions the terms and dates are on the brochure and that she spoke to the cashier and everyone is trained in the same way.. Anyway I asked her what was the actual words the cashier said...the response is there is NO SOUND....I said okay so why are you watching the footage and how can you establish the conversation? Denise said they are judging my sisters reaction....my next question was "are you qualified/do you have a degree to judge her reaction?" Basically I was told the cashier said she did not say that and that my sister may have misinterpreted what she was told....although there is no way to actually establish the actual conversation!!!!!