That proof should be enough to convince them. Give it a try. There is no harm. It is your hard-earned money after all. Even if they just call them, it will send a clear message to the estate agent that you are making things tough for him. You may also report the matter to the police Head Quarters located near Crazy signal. They have department known as "tafteesh" there. Possibly, they help may you by just calling the estate agent. If they do, it may give the estate agent a bit of a shake which may result in him returning your cash.