Hello MasterWarrant04,
Welcome to Apple Support Communities!
We want to help resolve any billing issues with your iCloud subscription.
See here to add a valid payment method:
"Add a payment method on your iPhone or iPad
- Open the Settings app.
- Tap your name.
- Tap Media & Purchases, then tap View Account. You might be asked to sign in with your Apple ID.
- Tap Manage Payments.
- Tap Add Payment Method.
6. Enter the payment method details, then tap Done."
This Apple Support page has the full details: Add a payment method to your Apple ID - Apple Support
If you need to speak to Apple about your bill, please reach out to an Apple Support Advisor for further assistance: Get Support
We hope this helps to resolve the billing issue so you can add a valid payment to your account.
Cheers!