What can i do about a mover who agreed to one price and now had changed his mind?

I hired movers off of Craig's list to move a few of my things, we agreed to one price and at the time we where only able to move half my stuff and agreed that he would come out later and pick up the rest. At the time I just paid him the whole amount of the move (I know I should not have done that) now I am trying to get him to come and get the rest and he keeps putting me off and now has told me for the amount of stuff that I have I didn't pay enough and is now refusing to give me back half of the money that I gave him, so that i can pay another set of movers to move my stuff, what can i do?