1. As per last amended Tenancy Act, the tenants shall have to pay the reasonable/fair rent.
2. However, the said reasonable rent fixed by the Govt. is also highly unacceptable in comparison to the market rate of the tenancy at your area.
3. Your suit claiming fare rent will take ages to be disposed of and after getting the Court order you shall find that the revised rent fixed by the Court is negligible in comparison to the rent prevailing in your area for similar category of premises.
4.So, it will be financially prudent on your part to sell off the said property to the developer who will be able to evict those tenants in ways which may not be termed as lawful.