Breach of contract - IT service company

I came to United States on H1B visa as an employee of a major Software service company. Before coming to United States, they had emailed me a contract that I have to return to India and serve for 6 months in India else I have to pay $10000 as liquidated damaged to them (As they have spent money on visa, travel etc). They asked me to sign a printed copy of the contract and send it back to the. I didn't sign as I didn't like the terms & conditions. I resigned from the company 11 months back and my resignation was accepted by HR. However, once I joined a new company they came back to asking me for $10000 and sent a notice to my address in India. They have refused to give me an experience letter and all the money they owe to me (retirement fund in India, leave encasement, last month salary in India etc). They mailed me saying even if I didn't sign a printed copy of the contract, any transaction done through their internal company website is legally binding and they will not provide me experience letter or the money they owe to me. This is a very common situation and I know many people in the same boat. Any help is highly appreciated. I would take legal help, if I have a good chance of winning it.