Awign Enterprises pvt LTD - Not received payment for delivering a service

We have worked for Awign for past one month and now they are denying one third of the payment. They are telling us that the client has not paid them so they will not pay us even. The payment that they have agreed for has also been delayed for more than ** days. They are doing fraudulent activities with me. This is the worst organization. I have been dependent upon them for the work but as I don't have any legal contract, I am not able to file a case against them. They have made full use of my efforts and now they are denying the payment. This is cheating. I am getting exhausted mentally day by day. This is causing too much stress. As evidence, I have a report from their team confirming the work I have done and the payment they are denying.