Sorry to hear about the clash with your placements. Unfortunately we can’t change the timings now as we had already announced this slot as the prelim timings.
PS: The placement - ICPC clash is as old as ICPC itself When I was participating, twice there were direct clash with ICPC online round. First time we convinced our college to postpone the placement test. Second time, I gave the online round alone while my team mates (who were in final year) joined later. Do try to work out something similar for your team. Good luck!