You are stuck in a difficult situation. The Real Estate Agent knows how to play around with you and how to make your suffer. Here are my suggestions that may cause problems for the estate agent and help you get your money back:
First, write a letter to Rental Dispute Committee explaining the whole matter and request them to help you get your money back. The letter must be in Arabic. Attach the copy of the receipt of payment. Possibly, they will help you out.
Secondly, lodge a written complaint with the police at the Central Police Station located at Crazy Signal. This letter must also be in Arabic. They have a department of investigation. There are police officers present at this station who speak English. They will call the estate agent and get him to refund your money. However, if the estate agent still refuses to do so or plays with time making promises after promises, the police will be left with little option but to advise you to file a case against the estate agent.
Third, lodge a case against the estate agent at the Sharia Court. This is going to be difficult process for you. That's because of several reasons and the people at the estate agent know this well. Should you file a case at the Sharia Court, you will need to to be present at the Court on every time a date for hearing is given. The estate agent will deliberately avoid the hearings giving one excuse or another. As such, it may take several months for the Court to give a verdict. During this period, you will be helpless. The estate agent knows this well. To lodge complaint, you may need the assistance of a lawyer. There are usually some of them hanging around the Sharia Court looking around for clients.
That's how the ball moves in Qatar. The majority of Real Estate Agents in Qatar are crooks and you will get to hear many stories about them.