I bought off plan property in Ajman Emirates city,...

please provide us with you inquiry in details, and we will provide with the respond as soon as possible according to the mentioned facts. 

You have to report the fraud incident to the police to be trailed according to the federal  penalty law.

Article (399)

Detention or a tine shall be imposed upon any one who seizes, for himself or for another, a movable property, or obtains a document or signature thereon, cancellation or destruction thereof or amendment thereto by fraudulent means, or by assuming a false name or capacity, where such an act leads to deception of a victim and leads him to surrender. The same punishment shall apply to anyone who disposes of real estate or movable property knowing that such a property is not owned by him or that he has no right to dispose thereof, or if he disposes of a thing knowing that it has been previously disposed of or contracted upon, provided that such acts cause damage to a third party. If the subject of a crime is a property or a bond which belongs to the State or to any of the authorities indicated in Article (5), it shall be considered an aggravating circumstance. The attempt of an act shall be punished by detention for a period not exceeding two years or by a fine not exceeding twenty thousand Dirhams. However, when a recidivist is sentenced to a penalty of detention for a period of one or more years, a maximum period of two years' police surveillance may be awarded to him, provided that such surveillance not exceed the sentence inflicted upon him