Hey Cowgirl, I do not know what format you use for collecting pay for lessons, but I am assuming there are liability issues that are waived with some sort of a signed contract. Perhaps the price structure could include a lessons cancelled clause with amnesty for one, but pay for any others without two day notice... That would be fair and not unusual.
It is no good fuming. Some of your agreements are barter, but you are so creative, you could probably figure out ways to shame these other slackers into keeping their obligations. You do not have to be home or around for weed spraying, right?
Phoenix is missing you. He has even visited the lonely and pathetic hopefulness site looking for you. Take pity on him. He can calm you down!!