As a phpVMS Forum member and developer, i want to point some things. When you are accepting an offer from a developer, you should not send the full payment before you are sure that your website will be OK. Of course, the developer has the right to request a deposit in order to start the project. Also, i would suggest to you to do all the payments via PayPal. As i remember, you have 45 days to open a case on PayPal and request your money back from the person you got the money. Of course, you should be able to prove it. Last but not least, although i do not know what has happened because i have not heard both parts, in many cases the deposit is not refunded. If you as a client decided that you do not want the website, the developer can keep the deposit.
All these are based on the terms you have accepted. Personally, in my offers, i include a list of terms in order to ensure the safety of both parts (me and my client's part).