Why partially paid invoices are marked as fully paid?

One of our vendors is also a Quickbooks customer and sent us an invoice through Quickbooks. We made multiple partial payments over a few months and everything looked correct until one day Quickbooks deducted more money from the invoice than we actually paid. This happened a few times until the invoice was apparently paid in full. We checked all of our bank records and are certain that we still owe $1,200 to our vendor.

We spent hours trying to report the bug to Quickbooks in various ways with no luck. There's no way to share the screen with Quickbooks, no way to email, no way to send screenshots, etc'... Chat agents kept transferring us between departments when in reality we just went back to the same department and had to start the chat all over again a few time. There's also no way to receive a copy of the chat via email.

We decided to post in the community, but looks like there's no way to attach more than 1 screenshot so that's useless anyway. We are now worried that payments we receive from our customers aren't recorded accurately also. How can you trust a software company that process large payments and doesn't allow users report bugs?