Unfair employment termination

I was recently appointed by a company where I had an altercation with an employee and I was asked to discontinue. The reason they gave me was I wasn't doing my job properly, I did not behave with the colleague, I did not submit required documents. Except for the altercation all other charges are baseless and I have proofs for everything. I worked for 11 days and also spent on company travel and had submitted an expense report. Company is refusing to pay this amount. There wasn't any induction done, there wasn't any warning given for so called misbehavior, which ideally was the job of HR before they could take such extreme step. This is playing with career. What do I do now to get the reimbursement?