Hi Chausse78,
If you have an active subscription, then you'll need to add a new payment method first. Then remove the older, incorrect one. This was mentioned on the page viewed before posting. In case you missed it:
Update your payment method on your iPhone or iPad
1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.
4. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Delete.
If you need to change or update your Apple ID payment method - Apple Support
If you're still not able to add the new payment method, you'll want to contact apple Support for help.
Get Support
Take care!