Thank you for your feedback. I'm sorry, but I can't reproduce the issue. Make sure that the other office buildings are really city halls, not some other type and that they are properly staffed. Out of curiosity, what buildings do you use? 600 sounds like a lot. Also, do you use the default settings.ini file or have you changed anything there? You could also post some screenshots of your situation (before and after building the new offices).

They are surely city halls, they have the same functions. I didnt changed any files.
These buildings are fully stuffed, but somehow they dont produce any services. I mean there are about 1500+ people work there everyday with 30-50% of them with high education but still obly 600 services everyday :\

I even reduced employees in the offices for half and still have almost the same amount of services :\

OK, then please answer the rest of my questions, give me a link to the building which gives you 600 services and provide me screenshots of your game (before building those 15 other offices and after it, with a visible menu of one or a few of them).