I'm not sure if your english is getting in the way but basically you don't go after the subcontractor. You go after the main contractor, the guy that you paid to get the work done.
However there is no legal prohibition against installing an airconditioner that drips onto the ground outside (unless you live in a HDB flat).
condominiums may have by-laws against doing that but if you did not tell your contractor, he's not responsible.
Look at it another way, you saved some money from not installing a condensate pipe that goes back into the apartment. Now you have to spend it to get that done. There's no such thing as a free lunch.