1. Complete search in respect of the property is required to be conducted at the Registrar's office and also at the Courts to be sure that the land to be purchased is free from any encumbrances/defect.
2. The fact that the said land has been declared as wetland will not be mentioned in the title documents but in the website of the concerned department dealing with the Wet land. So, proper pre-purchase property search is very important to ensure safe purchase of land.
3. Since it is in connection with a plot of land without any construction thereupon, you can not approach the Consumer Forum.
4. You have already taken too much time to understand that you have been cheated by the seller. You should now lodge a police complaint immediately against the said seller bringing the charge of cheating of you by taking money from you for selling the unsaleable piece of land.
5. If police refuse to register FIR against the seller, file a Writ Petition before the High Court praying for a direction upon the police to register FIR, investigate and act as per law based n your said complaint.
6. Simultaneously you should also file a Money Suit praying for refund of the said amount paid by you with interest, damage and cost.