What can I do if the employer does not pay full and final settlement?

Dear Sir , I am a retd defense personnel ,In Dec 22 i was contacted by a firm to represent for conduct of trails for Army ,I was also offered a payment of Rs 5 lakhs ( as per contact sent online) and reimbursement of expenses ,with an advance of Rs 1.5 lakhs ( 1.35 Lakhs was paid to me as advance) . I proceeded to HA Tawang for trials in Jan and returned on the 22nd Jan,the trails were conducted successfully and the Company was selected as one of the top 4 bidders.In Feb I sent the bills for payment ,the company reimbursed the expenses ,however they have till now not repaid the balance amount of 3.5 lakhs. On calling them the reply received is that the boss is out or F/Y end,or some other excuse is given. The company is located in Dehradun and I am loc in Banglore What can be done ,kindly advice. KK Nair