Management did not look at proof when it was given and requested a picture

Today my mom bought a Anthuriumm M/Day 14 cm, barecode ********** 943123 , sell by date 05/06/2019 with the amount of R 229.99 at Checkers riverside boulevard at 11:10:52 on 110519. The one had an sticker with 50%off on the shelff. The one she took hadno sticker on and she asked if it was 50% off at the teller. Management came and authorised the discount. We went back later to get 2 more. I took the slip S045028 for proof that my mom dit buy the same product for half price. The management, there were just 2, did not look at the slip and requested a pictureof the plant. Why would they want a picture when i did have the slip with me, they have their system and security cameras. As i reasoned for the price as it was given just 1 and a half hours ago the one manager had an bad attetude, i talked to her while she looked away and was starting to walk away while i was talking. They keep explaining that it was because of the expiray date. The other employee, had a better attitude but took the managers word that the product expired today. I have proof if needed