So this very large company who shall remain nameless distributes a proprietary software development environment that includes a patched version of a certain, well-known open-source debugging tool.

The patch is to make said open-source tool support their products. It's not even hidden or anything: the binary is sitting right there in the installation directory, it's called the exact same thing the vanilla debugger is called and when I run it on the command line, it clearly says "patched for xyz".

The tool in question is distributed under the GPLv2 and I need to modify it for my own project. So I sent an email to the company to request the source code for their modification, but they refuse by playing dumb and pretending they don't understand the question. They keep telling me the source code to their IDE is not public. I keep telling them I don't want their IDE but the source for the modified GPL backend tool they bundle with it. But no: they claim it's part of their product and they won't release it.

Anybody knows the best course of action to deal with this? It's the first company I've dealt with that explicitly refuses to honor the GPL. I don't even think it's malice: I'm fairly sure the L2 support guy handling my ticket was told to deny my request by his clueless supervisor who didn't bother escalating it. But it's also a huge company that's known to be aggressive and litigious, whereas I'm just one guy and I'm not lawyering up over this. I have other hills to die on.

Who should I pass the potato to? The FSF?