Let me help you resolved your subscription issues, @finance-in-i-far.
First, can you tell me the exact error you've received? This is for me to narrow-down any investigation that may have caused the issue with updating your subscription payments.
Meantime, here are the factors you'd want to consider when updating your billing information:
Ensure that all Billing & Subscription fields are completed.
Verify credit card details.
Confirm that the address for the credit card matches the address in your QuickBooks settings.
Make sure there are no special characters or symbols (such as @ or *) in your billing address. Special characters will cause errors.
QuickBooks only accepts the following debit and credit cards: Visa, Mastercard, and Amex.
Let's start by accessing your account using a private or an incognito browser. You can use either of the following keyboard shortcuts:
Lastly, I'd suggest contacting our Customer Care Team so we can further assist you in resolving your subscription issues. A specialist can securely access your account and securely review your billing details. Here's how:
Go to the Help menu.
Click the Contact Us button located at the bottom.
Enter your question and click Let's talk.
Choose either Start a chat or Call us.
I've added these articles as additional reference: