Fuller's Online Shop Gift Card

bought some gift cards for my elderly relatives to be used for a meal in there local pub around the corner. they tried to buy a meal with them they were told it was a franchise pub and they could not use them. I have bought these vouchers before and they were able to use them. As they are elderly and one has a serve disability they cannot use them anymore, sent a message to fullers but they didn't reply. So now they are are useless to them as they cannot travel. Help