We have a toilet flush (Geberit, one which is inside wall) in which suddenly the small button stopped working. The bigger one is working fine, so it's not a blocker as such. I'm wondering whether agency will charge us if I inform the agency to fix it. It seems, it needs to be cleaned or replaced (geberit heberglocke) as the lever may got calced over a period of time.
Presumably you're renting. In that case, the procedure it not to get it done yourself. If you call in a plumber, you will definitely have to pay their bill yourself.
Instead, call the caretaker of the building, who will either come by himself, or decide to send in a plumber. Unless you have damaged the flushing device (which sounds unlikely, from your description), you will not be charged. But in any case you should ask your caretaker about this.
Sometimes, caretakers wait a while, especially when there is no immediate urgency (and as you say, you can still flush the toilet) until they've collected enough calls from various apartments to make it worth their while to call out a specialised service, such as a plumber.
There's a push-rod inside...it's probably become disconnected. (Cracking is not very likely with those mechanisms, but I guess it could happen.) If that's it, repair is simples.
Thank you All. I have managed to open the Geberit plate at the wall (opened the very next plates etcs looking at videos in YouTube - quite easy to do), however it seems, the small push button one does not really flush. I tried to lift the same lever up by hand, however it still did not flush (while main one does). I think, the lever got damaged due to calcium build up over the period. I really did not want to lift up heberglocke as I was scared that I won't be able to put it back in place. I will let the caretaker of the building know about it.