You cant just back out of something, giving a deposit has an implied understanding that there is no going back, you are decided. Giving a deposit is there for security, so he cant just walk away on you, whats the point if you refund it to anything?

AMF, you clearly have no understanding of how a payment structure works. Youve never designed/programmed for someone with a deposit, have you? All of your solutions require the programmer to get burned and the client to get everything, even though hes the one who went back on the agreement.