I guess I have a different take on this topic. You definitely should complain. Not necessarily about the CM but about the confusion that led up to the encounter. My first career was in a customer related field and they made a big deal about the importance of complaints. If you don’t complain, they don’t have any way of knowing there was a problem. You did not have clear information about where you needed to report to gain entry for your ADR and, obviously, did not see the signage that gave that information. I would also say there was a training issue with the CM you encountered - you should have been directed to the entrance for early ADRs. Give as much detail as you can when making your complaint: day, time, location, CM’s name, etc. The more professional you can keep your complaint the better. You never know when you will get a little pixie dust in return.