client is not paying

[#1]

The contract was a fixed contract and the first milestone got paid, then he didn't set up more milestones, I got paid through bonus option, till lately I was requesting for the payment for the work that was completed, he refused to pay and the reason he given was that the payment i received two months ago is wrong payment, which is not, now he insisted the payment two months ago was wrong and refusing to pay for the work I've completed for lately. I've contacted customer service but it wasn't helpful, as the bonus payment is not under protection. is there any other ways to make the client pay for the work I did?

[#2]

No, since you were working without funded milestones, there's no way to make him pay.

[#3]

Ok, thanks Tiffany. lesson learned.