我充值了我的苹果商店礼品卡，却无法使用。
我想购买软件的订阅付费，但是生成订货单后，无法付款，付款不成功，我明确我已经兑换了我的礼品卡， 礼品卡有10美金余额，但是无论如何都支付不成功。
iPhone XS Max, iOS 15
See the following Apple articles:
Add money to your Apple ID balance
Add money to your Apple ID balance – Apple Support (UK)
Payment methods you can use with your Apple ID
Payment methods you can use with your Apple ID – Apple Support (UK)
What type of gift card do I have?
What type of gift card do I have? – Apple Support (UK)