This is the way of getting some money from you.Write them a letter mentioning the reason for leaving(late pay in ur case) and also reach out to vendor.

This had happened to lot of people.

 Don't worry about the letter, I bet they have more to loose than you coz' they do all kind of  fake things, after all its a dhoti company. I bet they cofirmed your work history too and many others. Reply them with what you got on them... all the fake things that they do and the tax fraud and most importantly the USCIS..I'm 100% guarenteed that they will not go for law-suit. Its just a threat. Please mention the name of the Consulting Company if you don't mind.

Legal Department ??? in dhoti consulting where they do all the illegal stuffs, that should have been illegal Department...    

1) Ask them for a copy of contract that you had signed
2) Read it carefully. Certain clauses could be unenforceable.
3) If they sue you, they will have the citation delivered to you.  Read the allegations. Just respond within 20 days (most likely in 20days if your state also follows the standard Federal Procedure.) Your response would be "General Denial", which means you deny all the allegations in the suit.
3) After that do nothing
4) The burden is on them to prove that you did something wrong.
5) If you think the allegations are baseless, file a Motion for a Summary Judgement for Dismissal with Prejudice.

Above all, get the contract first.

 I had similar case. But when I replied them with the email attachment that they sent to me.. saying that I will file a complain with labour department about your forgery n how you ppl put the innocent in trap, they shut their mouth and paid my remaining and everything dismissed.

Email was like this :