Ask HN: What to do about wage theft?

I was working remotely at a US company via an outsourcing agency in Singapore for about 8 months. The US company suddenly fired me in the middle of March. It was a complete surprise to me; my boss only said that it was because I was late delivering something and admitted that he hadn't warned me that my job might be in danger but since I was "a 30 day contractor" he didn't have to. (I had reasons for being late, and I had been keeping him informed about them).

A couple of days later the CEO of the outsourcing agency sent me email saying that the US company had discontinued my contract effective 30 days from then and that I should bill March normally and then submit a final bill in middle of April for a partial month and that I would be payed out my unused PTO. And so I did, but no money arrived and the CEO of the agency is no longer answering my email.

Do I have any recourse here or am I out out luck?