Sent Home with No Job

I took a job at a school a LONG drive from where I live. I got there and they told me that there was already someone in the room to sub. The teacher had called her and she had accepted the job - only instead of accepting the job officially, she just listed herself as "unavailable", which meant that the sub caller COULDN'T call her - and I took the job instead. So when I got there, they sent me home. They do have some rules and I could have insisted on the job, since I had the job number. But when the teacher had asked for that specific sub and she was already there, I didn't feel like insisting.  They did offer to find me another job, but I am too picky to take any old job that they can't find anyone else to do. That part is my own fault. I have been stuck sorting mail, filling in for study halls and detention rooms, shelving books, and photocopying and I just don't care to do those things.  And, since I chose to leave, I did 45+ miles of driving for nothing - not even mileage. They have lots of other jobs available for today, but they aren't ones that I would normally take, so I am back home. Too bad for them. 

Subbing is the pits. Sometimes. Several people have suggested to me that I find a different job.  I have actually looked into doing so, but my computer skills are not current enough to get a decent job in IT.  I am overqualified for jobs I could be hired for and underqualified for jobs I would be interested in.  I actually enjoy subbing on good days.  I just wish there were more good days.