I’ve actually had this happen twice so far to me. I’ve gone in for interviews and the lady wasn’t in. No one bothered to tell me.
I would call and ask to speak to the manager but not tell them who I am. Once I know he is there, then call back and state who I am.
I wouldn’t go in, as it puts the manager on the spot and they might not be uncomfrotable.
In both cases where I went in for an interview and was stood up, what I did was issue a follow up email and call the next day. One lady I never got through to and the other said, the job was already filled.
One thing I learned about this “new economy,” is very few companies have any interest in showing you any courtesy. I can’t tell you the number of interviews I’ve been on, where the interviewer has answered their cell phone and taken a personal phone call.
But I wouldn’t go in. you don’t want a face to face confrontation. If it was an honest mistake the interviewer may feel so uncomfortable it may hurt your chance. If you call and leave a message and he was sincere, he’d at least phone you back to say, come in later on or that the job is no longer available.