grannyactivist
I’d call the brother and tell him you bought something at JL and discovered the amount on the receipts didn’t match the value of the cards. I’d say you wanted to let him know in case there’s been a mix up: if there has, what would he like you to do? and if not you want to thank him for his very generous gift this year.
This definitely, why would you keep quiet? someone made a mistake the money is not for you give it back and see what happens, If they get embarrassed so what. You could use the time to suggest you stop giving present as it is a farce anyway. Particularly as it sounds like you are not overly fond of them anyway. Personally I would have told JL that you only expected the £50 as you were told and asked her to revert the sale, I would not have spent vouchers which were not intended for me.