How can I change my payment information for my subscriptions?

Change, add, or remove Apple ID payment methods

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID. To add a payment method, tap Add Payment Method. To update a payment method, tap the payment method, then edit your information.

Hi, you will have to contact apple support

https://support.apple.com/en-us/HT204169