I need help!! My bathroom sink has one of those metal stoppers that you push down to close, and push again to open. This probably isn't the right way to describe it, but I've no idea what these parts are properly called. I'll pop a couple of pictures in as it might not be clear what I mean. Anyway, this morning it jammed when it was closed, and I can't get it to open. I've tried filing the edge a little bit, but it's jammed - I can push it down a little way, but the catch doesn't release.
It sounds like such a small thing but I've no idea how to fix it, and my sink will be unusable until I do. Any ideas? If I have to ask a tradesperson to help, I've no idea what kind of person or how to describe the problem! I do hope someone can tell me what to do, please and thank you.