I went shopping at a big retailer and used a gift card to pay part of my total. I was at a self-checkout, and when I scanned it it wouldn't work. The shop assistant came over and also failed to get it to work, I said 'don't worry about it, I'll just use the gift card another time' but the assistant then asked what my balance was on the gift card, and then manually removed that amount from my total. I had handed them the gift card and thought that they had taken the gift card with them. However, as I was leaving I grabbed my receipts and saw that the gift card had been left at my self-checkout too so I just grabbed it along with the receipt without thinking and then went on with my day.
I just checked the balance of the gift card and no money has been deducted from it. For context, the gift card isn't for that retailer specifically, it's a third party gift card you can use at several different shops.
I have my receipt, WIBU to go to a different branch of the retailer (this wasn't my local branch) and hand over the gift card?