Cancel this option, okay?

I suddenly received a phone call inviting me to an interview. It was almost noon at the time, and I told the other party by phone that I had another interview scheduled in the afternoon, so I would have to check whether I had time to attend the interview.

I also said that I would call back to confirm whether I could attend the interview. After finishing the afternoon interview, before I had even called to ask, I received a message from the job bank saying that they claimed I had stood them up?

May I ask, if the time was never confirmed, how could I have stood them up? Such a fragile company, haha. No wonder the online reviews are all unfavorable.