Unable to make a purchase on Apple Store using apple account balance

I originally sent my old iPhone 13 Pro Max for a trade in to get a $305 gift card, which I intended to use to buy new AirPods Pro 3 and a Belkin screen protector for my new iPhone. The total was $312.79. When I applied my gift card and also added my personal debit card to pay the remaining $7.79, it was declined. I tried my credit card as well, it was also declined.

I made a call to apple support who said to not split my payment, and suggested I redeem the gift card to my apple account and add the remaining balance to my apple account as well. So I have $313 in my apple account. Again, when I tried to purchase by applying my apple account balance, it declined on both the Apple Store app and the website. I called apple support several times, and they gave me an updated ticket email that said it was resolved, but I went back to the website, tried to purchase again, and got the error message:

"Items in your order are not eligible for this payment method. Please select another form of payment."

This has been extremely infuriating and misleading. I would not have redeemed that gift card in the first place if I knew I couldn't use my apple account balance to pay for what I want. I have $313 stuck in a form I cannot use and absolutely had no intention of using that money for games/subscriptions/music and such. I just want my money back in a form I can use like apple cash or just purchase the products I want/