We all have "that vendor" right?

In my 25 year career, I have never had to deal with such a garbage software vendor as this one. I don't want to go on a rant since I have other things to do today and could go on for hours, but here are the highlights:

• Application has like 30 modules. Each module has its own config file.
• Config files are not centralized and reside in the directory with each module.
• Vendor ships a zip file of slop code that requires manual assembly.
• Vendor provides no substantial documentation. Every request for technical documentation is met with "Let's setup a meeting to solve your immediate problem".
• Vendor ships dummy config files in every release necessitating manual backup/restore of the config for each of the 30 modules
• Vendor changes config file format every third release. This requires re-configuring the entire application stack and all 30 modules.
• Vendor puts the version info in the goddamned config file instead of building it into the compiled .NET application as a variable like a sane person would do.
• Vendor sends an update every week and gets pissy when we don't deploy it within 3 hours of their "we shat out an update" email.
• Vendor has been asked repeatedly to address this. The only response we've gotten to these complaints is the sound of crickets chirping. 🦗

To answer any questions:

1. Yes, I voiced my concerns long ago. They were ignored.
2. Yes, they are the "lowest bidder" and it goddamned shows.
3. Yes, they know I hate them.
4. Yes, I tried writing scripts to manage the config files. They work once or twice until the vendor changes the config file format every 3rd-4th release.
5. Yes, it is sunk cost fallacy all the way down, but I've been given my orders.