the new connector fails if it tries to process an order which has the same order number as a previous transaction on QB, how to resolve?

Hi there, @PaulK4. I appreciate you reaching out and sharing the details of your concern.
 

If you're using the eBay connector by Intuit, I recommend contacting our Live Support Team for more in-depth help. They have specialized tools to access your account, conduct a screen-sharing session, and thoroughly investigate the issue to provide the best possible resolution. Rest assured you're in good hands.
 

Here's how:
 

1. Sign in to your QuickBooks account.
2. Click the Help (?) icon.
3. Scroll down and select Contact Us, then follow the prompts.
4. From there, you can request a callback or start a live chat with an expert.
    

For the business hours, check out this article and look for the Support hours section to ensure the team is available: How to get help with QuickBooks.
 

However, if this is a different connector, I recommend contacting the developer of the application directly for more assistance regarding its functionality and setup.
 

We're here to help if you have further questions or concerns.