Saw an ad on the building for an exhibit I really ...

Saw an ad on the building for an exhibit I really wanted to see. Went to the website and found the exhibit wasn't scheduled to be there until next month. Okay, I understand. Went to the museum anyway. Paid a lesser amount to get in, and when we asked why, we were told the museum was only open for 1 exhibit. The website did not indicate only 1 exhibit was open, and there was no signage at the entrance indicating this either. We were extremely disappointed.