Desi Consultancy Threatening with Legal Notice

I got a call from Desi consultancy recently for a Job requirement and have asked me to sign the Non Competence Agreement /Personal Agreement to submit it to the Client for Interview. Salary was fixed as 110000 for Full time. I have cleared the Interview. Later they informed me that they will give 85K as Full time salary and difference will be paid as Bonus every 3 months. Later i found that their medical insurance in too high (Expecting Kid in next 3 months) and they are not providing the Relocation/401k and other benefits which we normally get for full time. Two Days latter, i have emailed them that i cannot join them. Yesterday they have sent legal notice to me that they will start lawsuit against me if i did not join them.

Note: I have not signed their Offer letter and H1B transfer is not yet started.

Please provide your thoughts whether legal action is valid in my case and some one can share their personal experience if they have faced this Previuosly.