The tenants are not leaving and claiming the property as theirs

We own a 3000 sqft building which we bought about some 9 years back. There were tenants in the building who refused to leave the building and they do not give any rent too. Above all that they claim the building to be theirs. Its very clear that they are trying to cheat and they have political support too. This property totally belongs to 6 people including us. And all of us are ordinary middle class people ,who invested our lifetime earnings in this. by now we have given about 22 lakhs (which we brought for loan ) to them to leave but they did not do so. For filing a case in court, others are afraid that it may take years to finish off the matter , so they are willing to file up a case. I want to know whether if we file a case in court , will it be positive for us and how long would it take?