Apple wallet / iCloud storage issue

1.

What is the problem with my apple wallet purchasing method ?

In Wallet app you can add a credit, debit, or prepaid card.

See the following Apple articles:

Set up Apple Pay

Set up Apple Pay - Apple Support

Set up Apple Pay in Wallet on iPhone

Set up Apple Pay in Wallet on iPhone – Apple Support (UK)

Apple Pay is the way to pay. It replaces your physical cards and cash with a method of payment that is private, easier and safer. Whether you pay in a store, on a website or in an app. This is the new payment.

it is actually the same as paying contactless with your bank card, only via the iPhone.

See -> Use Apple Pay for contactless payments on iPhone

Use Apple Pay for contactless payments on iPhone – Apple Support (UK)

2.

My payment methods have funds available for purchasing yet I am unable to pay iCloud plus for more storage.

That means that you use your Apple ID balance as payment method.

See -> Add money to your Apple ID balance

Add money to your Apple ID balance – Apple Support (UK)

If you have add funds to your Apple ID balance, it would take about 1 to 3 business days in order to process.

Yes, you can pay for iCloud+ with your Apple ID balance.

See -> Check your Apple ID balance

Check your Apple ID balance – Apple Support (UK)

-> check next week your Apple ID balance.

You need to change your payment method, see -> Change, add or remove Apple ID payment methods

Change, add or remove Apple ID payment methods – Apple Support (UK)

 -> use your Apple ID balance as payment method.

3.

Check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 2 TB) then you have an iCloud subscription.

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

If you have upgraded iCloud storage, it would take about 1 to 3 business days in order to process.

Once your request for iCloud+ has been activated, you should receive an invoice in your email box.

Get more help -> Contact Apple Support -> Get Support (apple.com)