I appreciate you for the update and screenshot above, @Accounts SA. 

The error code -81624 means the payment authorization failed when updating your credit card information in QuickBooks Online (QBO). This may be because of an invalid address or the details you've entered isn't match with your financial institution. With this, you just need to make sure all the details are correct. In case everything is right, then I'd recommend contacting your credit card provider to verify your account.

Once verified, you can update your payment information for your QBO subscription again.

In case the issue persists, I'd recommend contacting our Customer Care team. They can securely pull up your account, identify the cause of the problem, and walk you through to successfully execute the process.

In the meantime, I'm adding this article to further guide you in effectively managing your business using QBO: Help Articles. It includes topics about VAT, banking, customers and income, and suppliers and expenses to name a few.

Please know that you're always welcome to comment below if you have other concerns or follow-up inquiries about managing your QBO subscription. I'm just around to help. Take care always.