I think telephoning is kind of like a happy medium. If this had been a long-standing, close relationship, then of course it would be much more appropriate to have closure for both of you. Since it doesn't sound like that is the case here, then an emotional closure probably isn't necessary. $170.00 IS a lot of money and you do have a right to consider that important. If you were to just leave an e-mail or mssg., it sounds like you would not feel good about this. The phone call would make it personal and caring, yet it saves you the money and would require you to feel uncomfortable for only a brief time. Your scheduling conflicts give you a very good non-personal excuse.
Good luck!

tulips