Breach Of Contract, Recovery Of Dues

We are doing corporate services as per company guidelines. We were associated with BTI Payments Ltd in their division INDIA ONE ATM on a service channel partner contract for five years. This agreement implemented from September 2015 onward for five years. But they have paid us till July 2016 and stop our payment further without any confirmation and mail us that they appointed someone else to do the work assigned to us. So we ask them without any mail communication or any written information why this is happening. One of the employees has taken his personal interest with somebody and start paying them whether we are already working for three month but when our claim not received on a monthly basis so we will have to stop working and asking for my payment then they said only security deposit will be refunded. So we fight for our monthly claim. In this regard they given written termination letted on 25th of February 2019. So we are asking our office expenses till termination.