Shoppers Drug Mart complaint: $100 Home Depot Gift card wasn’t set up properly by store clerk

My daughter bought me a Home Depot gift card in May 2019 from Shoppers. It has no expiry date. I went to use it in August 2022 but it didn’t work. Home Depot would do nothing without a receipt from Shoppers. We contacted Shoppers and provided them details of the purchase (between 12.00 noon and 1.30 pm on May 22nf, 2019) together with a copy of a credit card statement showing a purchase on that date for an amount over $100. While we had kept the receipt it was a thermal print and most of the details, save for the date, had worn off. Shoppers would do nothing to help as apparently they keep copies of receipts for only one year (yet Canada Revenue Agency expects me to keep receipts for six years!).
So, a $100 gift card with no expiry becomes worthless due to an error by a store clerk. In effect SDM are virtually saying that the card wasn’t paid for, even though it’s their error, firstly due to the store clerk not keying the card details correctly and secondly because they claim to keep receipts for only one year. They are putting all of the blame on the customer who only discovers the problem when attempting to use the card. I could go to small claims court I suppose and try to collect the $100 plus expenses (which would exceed the $100) but I am unwell due to being diagnosed with an aggressive form of cancer in October 2021.
Can you help? I doubt that I will be able to get past junior customer service people whose job is to deflect what they consider to be trivial complaints – I do not consider this to be trivial!