The art business

Well I had my first bad experience with the whole T shirt design thingy. So this band asked me to rework a design for them. Ok no problem I did so and then they approved it and wanted to pay me. I was thinking to myself nice that went smooth. Now they decide they want some more changes and said they would pay more still absolutely ok.. So late at night a get an email from them saying they want to go in a different direction and now they don't want it.......but wait they offered a 30 kill fee.....hahahaha so lame