I admire you for taking the time in telling us about your concern. I'll make sure you'll be guided to the right support available.
I recommend communicating with the Amazon support. They can further review your item set up and can provide additional troubleshooting steps to fix .
Also, may I know what card you used while trying to order supplies from amazon? This way, we can provide the best possible solution to fix your concern.
Additionally, here's a compilation of useful resources for the steps related to your business task while working with us: Help Articles for QuickBooks Online.
Please know that I'm always here anytime you have other concerns. Just leave a message below. Keep safe always.