I sent a patch to a bigger and more known software company, now defunct. I ended up writing some rude comments in the bug submitting form, after being forced to enter endless data about me, the company that I worked for and a lot of information about how to reproduce the error. Not proud of it, but I understand the GP: you're helping them and they treat you poorly.

They included the fix in the next version of the tool. I later noticed it was incomplete, but this time I just made the correction locally.