clicks expired pills

i bought a box of Centrum multivitamins for my grandmother last Friday at CLICKS ECO BOULEVARD, and went to drop them off her place, and the next day (Saturday) she called to let me know that the pills were expired. i called the store to let them know that they were expired and that i didn't have the slip, the guy i spoke to the consultant he said i must come to the store, so i drove 50km only to be told by the store manager that they couldn't exchange the pills cause there is no proof that i have purchased the pills from their store, even when i told them that i can show them the guy who sold them to me, cause he is the one that told me about the promotion that they were running.. if this is the kind of service that CLICKS is giving to their customer and selling expired items then i will never buy anything from your stores again.