How to collect money owed to me?

Question

I sent a $500 deposit to a private party for an rv rental. The private party informed me 3 weeks prior to the rental period that the rv was totaled. The party promised to refund my deposit in full. To date I have only recieved $120. After many phone calls and emails the party informed me that they were broke and would eventually get around to paying me. The period of time that I was supposed to rent the rv was 3 weeks ago.