30 Day notice period violation?

Hi We are a small IT consulting firm in NY.We had a contract with another IT consulting firm on corp to corp basis by placing employee of ours with their client with a notce period of 30 days.
The project is for two months with possible extension.After two months my employee requested other firm for 20 days leave for marriage,but they told us they want to replace him instead of sanctioning leave for him.They emailed our employee not inform the same to their client and they will take care of it.Then they emnailed our employee how soon he wants leave and he emailed them "in 15 days".so they considered that as notice and they didn't pay for the entire two months including employee expenses citing it as violation of notice period (30 days).My employee's time sheets+expenses were signed by client and client already released payment for the same to them.
As per contract they are supposed to realease first payment after 45 days of employment.
Can we get our payment back?

[annjd]

Yes you can argue they agreed basically. And he was not giving notice...You may sue in small claims...