Poor communication for day visitor times

I visited Warmbaths resort on 30/12/2019. As day visitors we were informed to leave at 17:30, however at 16:30 the facilitators start loudly blowing whistles and ordering all day visitors to leave the pools. Shouldn’t this be communicated at entrance as well, explicitly, that day visitors should leave the pools at 16:30 and the resort at 17:00. I was confused to see this and displeased. This times communication is misleading and it’s unfair that the 30min swim time is lost for day visitors.