Please am having issues with my account trying to pay on an account and is not working

See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

• if you want to use your Apple ID balance, you need to set your Apple ID balance as your default payment.

You can also -> Check your Apple ID balance -> Check your Apple ID balance – Apple Support (UK)

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

Get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK)