Metal/ wood staircase

You need a joiner, not a carpenter. "Menuisier" in french.
It's not a job that gets done often, so your chances of getting lucky on an expat who has renovated recently are remote.

Try Yellow Pages for showrooms.

This expat has had a new staircase and doors fitted recently.
I checked out 3 or 4 local showrooms before making a choice and the first thing I asked was whether they would fit whatever I bought. They all would and, if they would not, I would have moved on.