Q: iTunes

See this support document. Redeem iTunes Gift Cards and codes - Apple Support

See if this one helps. Otherwise, it could be when they were sold, they were not activated correctly. If you can't redeem your iTunes Store Gift Card or code - Apple Support

Are you located in the same country where your Dad is? Were the cards purchased in your country?

Then I suggest you follow the information in the second link that I provided. If that does not help, you may need to contact iTunes support for assistance. They may be able to answer your questions. Information for contacting iTunes support is in the second link I provided.