Nico, these people you have doing your programming stink. When you make a change in a program, you also need to find out what else it has changed, that is not being done!!!
It's one thing to fix a program error, but another entirely to create more problems with the fix, or not actually fixing the entire problem. These people really aren't fixing much, but they sure do create other problems.
I guess it's called job security, but not good for your customers. This has been out of Beta for years; we should not still be your testers.
Maybe as a suggestion, run your tests over the internet like we do, not connected directly to the servers hosting the program.