Shoppers Drug Mart review: issue processing my payment

The incident took place on November 9th 2019 at 9:00pm. I was in shoppers drug mart on Concession street, in Hamilton, ON, where I was trying to make a purchase using my gift card but unfortunately the computer was unable to read my card for some reason. The cashier that was assisting me said she is unable to process the payment but if I could go to the cosmetic counter, to make the purchase, where her manager could help me. When I went over the same issue happen and my card was not being read for some reason. I asked her if she was able to input the card manually? she replied she doesn't know how to do that so I asked for the manager and she said she was the manager. I then asked so what am I to do now and she asked if I can come back tomorrow morning ? I answered "no" paid for my items with cash and left the store. I then called customer service and told them situation, they told me I shouldn't have left the store that instead I should have called them if I had an issue and they could've resolved it or walked them through the process. I returned to the store, informed her I spoke with customer service and how they told me they can walk her thru the process over the phone, and would I be able to return my purchased items and repurchase them using my gift card? She then told me she doesn't have time that she has to close off the cash and she has to do shift change. This is a store that is open 24hrs. I left baffled, frustrated and unhappy.
I feel I should be reimbursed for the purchase I had to make out of pocket, when I had a preloaded gift card that I was unable to use at my time of purchase. I have my receipt