You have to give BSNL notice for eviction if they fail you have to file a suit for eviction and possession along with claiming the rent arrears.

You have to file suit for eviction for failure to vacate on expiry of lease agreement 

2) also claim penal rent as per terms of agreement 

A lease expires on the efflux of time after which the lessee is bound to vacate the premises unless the lease is extended by further time.

It is not clear whether whether you have them eviction notice or expressed desire not to extend time anymore.

In any time to evict the BSNL you need to send them first eviction notice and then file a suit for its eviction.

Though such suit takes time but eviction is inevitable conclusion for sure.

You can proceed with eviction suit after giving them notice. They will be easily evicted on ground of non payment of rent

You can file case in the court to vacate the premises or charge as per demanded rent. Before this you can send them legal notice via lawyer.

Issue notice to vacate immediately and claim huge compensation amount in default.

File eviction case and interim order for payment of arrear rent and the compensation amount. 

File a complaint to police that BSNL authority has not been allowing you to enter upon your property forcibly.

File eviction suit, ground of eviction will be default in rent payment and expiry of Agreement. Issue legal notice by giving 15 days to vacate.

When eviction will file, rent shall be payable till disposal of case, no payment than instant eviction.

If the tenant refuses to vacate after the expiry of the lease then you may move to court and obtain an order of eviction against him. Non-payment of rent is also a ground on which the lease can be brought to a premature end by the landlord by moving to court and filing a case for eviction. 

You should hire an Advocate and serve a legal notice to BSNL for vacating the premises through your advocate. And if they don't want to vacate increase the rent by making a new agreement.

If they fail to vacate the house or increase the rent you should file eviction suit against them.

You first issue a legal notice instructing them to vacate the premises since the lease agreement period has expired and you are  not willing to renew the lease agreement.

Failing to respond or comply with the demand made you may file an eviction suit in furtherance.

1. As per the information mentioned in the present query, makes it clear that the lease period has already been expired and now they are on monthly rent without any lease agreement.
2. You should give them a notice under section 107 of Transfer of Property Act.
3. Then if no response then should proceed to file a suit for eviction before the court of civil law/ rent tribunal, and demand for all areas of rent till the date of the disposal of the case with interest.