Money not returned

I'm a sole propreitor doing interiors business. I exeuted contracts for retail industry. In one such occasiion, I was assked to renovate the residence of a companys' MD with whom I was doing projects. Since this is a personal work (residence and not official), there was no PO and the work was executed on good fiath. The company project manager was liaising between me and MD and used to give us cash as and when we do the work. All the communocations were made in whatsapp message. Since the MD was not there, I have put my money out of my own pocket and completed the work. Of the total money spent I'm yet to recieve apprx.2 lakhs. The work was executed in Dec'19 - Feb'20. All these days the project manager was saying that he will talk to his MD and get the money settled but nothing is moving. I have sent a voice message explaining this to the MD and also an email in supot of the outstanding amount. But absolutely no response. Can you suggest how this can be taken legally. The only evidence avauilable is the messages communicated over whatsapp whcih clearley states that money will be returned. Your advice is much appreciated