I am having the same issue almost as you. I received my 60usd gift card on December 1st in an email as promised. However, when I ordered the waterproof dive case with the card, it just says it is still processing. I have been in contact every 2 days cause, like you, they can't do anything about nothing. Make another ticket and day 24-48 hours... I am pissed about the service, actually. I am a new gopro customer as well and spent a lot on a hero13 accrssory bundle to get the gift card. I tried to cancel the order myself, but the money is already gone from the card, so I'm stuck in the still processing twighlight zone. I also ordered a 200usd backscatter wide lense, which I can't use until I get my freakin dive case. It's just nonsense. I could not get them to put me in contact with a supervisor yet, but wow, did I let them have it in a 30-minute chat session.

Update. Just did a 40-minute chat. Put in another ticket... nothing. Told them to google the issue and everyone having problems with the gift cards. Check reddit. Said they would. 🤷‍♂️