Now, dad needs to grow up. If he was unable to pick the child up he should have called. Furthermore, being in day care all day like that, every day is not the best...kids need to be with both parents and cared for after school if possible. It is not a reality in every house hold and I realize that...if he understood that he would pick the child up.
Now was there a reason? Meetings? Work? Hit the bar? Did you ask why? And yes, hanging up is not the answer. It is a power struggle and he feels like you are trying to be in control. Maybe you made it TOO easy for you to be the fall back. Did the day care call him? What did he tell them? Just curious.
I am not saying you were at fault...he is an idiot obviously. However, make sure you are not setting him up for failure...what time do you normally pick him up.