Core-Mark AP Supervisor interview questions

Did a phone screen with HR. Several days later was asked to come in for a in person interview. Asked to interview on a Friday waited several days with no answer. The Thursday before they said because hiring manager didn't answer Id have to reschedule. Requested to interview on a Tuesday since I was off and now answer. Tuesday came and I followed up and was told the position was filled. Why ask me to come interview if you were going to fill the position?