Wanted to upgrade my plan. tried to pay but payment refused and got error message : There was an issue processing your billing information.

I've checked our records and haven't seen any cases the same as yours, Citruscreekplant. Let me help you upgrade your plan.
 

You may be experiencing some browser hiccups. We'll perform the basic steps to fix this. Let's start with logging into your account through a private browser. It's the best place to identify web issues. These are the shortcut keys:

• Google Chrome: press Ctrl + Shift + N 
• Mozilla Firefox: press Ctrl + Shift + P
• Safari: press Command + Shift + N

If you're able to upgrade successfully using the private browsing session, go back to your regular browser and clear its cache to refresh the program. It's advisable to delete them periodically to prevent and fix issues like this.

Also, you can use a different browser to narrow down issues.

I'll also include this article to guide you better: Upgrade or downgrade your QuickBooks Online subscription.

If there's anything else that you need, don't hesitate to let us know. Take care!