Hi shaaaw,
Seems you first need to sort out the payment method:
You may need to add the new payment method, before you can delete the old one.
Check below to make sure your payment method is an acceptable one in your country, or region
If needed: You can drag the payment method you want to use to the top of the list.
Apple support have articles online that may help guide you:
What to do if your payment method has been declined in the App Store or iTunes Store
If your payment method has been declined in the App Store or iTunes Store – Apple Support
How to see what payment methods you can use in your country or region:
Payment methods that you can use with your Apple ID – Apple Support
Manage App Store purchases, subscriptions, settings, and restrictions on iPhone – Apple Support
If you still need help:
App Store Support Website:
If needed: You might want to reach out to the App Store Support Team:
There is a "Get Support" link at the bottom of their website page that opens from the link.
App Store - Official Apple Support
or
Apple phone numbers around the world
Contact Apple for support and service - Apple Support
All the best :-)