Heating load calculation or room heating load

2,000 euros net from a locally based planning office for technical building equipment...

Remove one zero, then you have what a room-by-room heating load calculation + underfloor heating design costs net with specialized TGA planners. The costs your office is asking for are absolutely exaggerated.

Remove one zero, then you are at what a room-by-room heating load calculation + underfloor heating design costs net with relevant building services planners.

Do you have any other recommendations?

My recommendation of the TGA planner I had posted two pages earlier:
https://www.hausbau-forum.de/threads/heizlastberechnung-oder-raumheizlast.35095/post-406907

I am very satisfied with his work.