Case against Nagar Palika Nigam

My father own a property(Home) in Chattisgarh. The lease of land for the same need to be renewed every 30 years with Nagar Palika Nigam. The land was bought from Nagar Nigam long time back. When we build the house the measurement and the area was given by Nagar Nigam only but after the house was built they say that it is build on the wrong area. We have all the documents given by them, which indicates that the mistake is done by them during allotment. Since it was build on wrong land, there was extra space infront of the home and we took permission from CMO of Nagar Nigam for plantation and we have signed document for the same with us. Now as the land lease renewal time has approached, Nagar Palika Nigam is not renewing the lease and they are delaying it and not giving any answers. My father approached Forum court for the same and Nagar Nigam replied that they will only renew the lease , if we leave the area infornt of us , use for plantation, which they see as unauthorized and also they see this case should be in other law suit court and not forums court case. I have few questions here: 1. Is this forum court case? 2. We have all the required documents given by Nagar Nigam, (though they did a mistake by assigning the wrong area). What can be government orders on this?