Life / Plumbers' supplies or similar & plumber in Wrocław [2]

Is there an independent or small shop that sells sanitary/plumbers' supplies in the Borek/FAT/Karkonoska area of Wrocław? I need a sink drainage fitting (the screw in the trap or the whole trap). LM, Obi & similar do not stock the screw, only the entire part.

Also, what is the typical labour a Wrocław plumber may charge to come out and fit it if I cannot do it myself during the evening (18-19) please?

Thanks.

It looks something like this, however not exactly the same, but it's the metal screw that fixes the waste outlet to the plastic pipe underneath