14 DAY TRIAL // If you’re trying to redeem an iTunes Code, either from someone or from an actual iTunes Gift Card, Apple has some workarounds for you.
Apparently, the best thing to do when you try to redeem an iTunes Gift Card or code is to use your Mac’s / iPhone’s built-in camera.
According to the Cupertino company, “In some countries, you can use the camera on your Mac or iOS device to redeem your gift card. If you can't use your camera to redeem your gift card, you can still enter the code manually.”
If manually doesn’t work either, Apple says you should make sure you’re typing the right letters and numbers. “Some letters and numbers look alike, so it’s easy to mix them up,” according to KB article HT6021, which offers some handy examples. If nothing seems to work, contact iTunes Store Support.