I dont know exactly how to change the gift card. I think whats Important is the message you wrote to your father.
But you should contact them. For me they been pretty prompt with the responses. In 1 day.
Also As a remark I have not have no issues with these cards. I choose to transfer the funds in my bank account and every time the money were in my bank in 3-4 days as stated.

As i mentioned in a previous review, I purchased a gift card to a specific restaurant and they said they had never approved gift Rocket selling their gift cards. Luckily, they still honored it but I would never use Gift Rocket again. Not only do they charge an exorbitant fee, but many of the businesses have not allowed them to sell their gift card. Hopefully, Heart Attack Burger Grill will approve this card, You might want to check first if they do, and then let your father know. Good luck.