As sajamitra said, just walked in your own way and do your job. Change your cell phone and contact information. Even you signed the contract i.e.$60K per year. Then, you need to get pay check and tax. This is america and there is fair job practice. They are trying to get advantages from you, asked send all contracts/signed document. Even if they are keep on harassing, asked filed complain to labor department. You are not a bound labor for any shit compnay. 

Good luck for job  and stay cool without accepting any call/papers from them.

Thanks