Has anyone had an estimate being created for the wrong customer?

I can help you in recreating that estimate to the right one, @philip23.

There are times that you'll create an estimate for the wrong customer. However, you can easily delete it and recreate to the right one. Let me show you how:

1. Click the Sales menu and choose Customers.
2. Select Estimates from the Money Bar. 
3. In the Open Estimates column, click the estimate to open them.
4. Tap More then Delete. 
5. Choose Yes when asked Are you sure you want to delete this estimate?. 

Check this article for more information on how to delete and create an estimate: Set up and use estimates.

Also, here's more information on how to convert an estimate into an invoice in QuickBooks Online. 

I'm always here if you need more help with your estimates. The Community is always here to assist. Have a wonderful day!