MY OLD COMPANY IS NOT PROVIDING ME THE SALARY, EXPERIENCE&RELIEVING

Hi, I am Girish, I am working in a company called Cedron Software Solutions, Bangalore, when I attended the interview in this company, company HR told me the notice period would be of 15 Days and they told me that I will be getting the offer letterdirectly by hand when I join that company. I agreed and i joined as per the DOJ and after joining also they didnt give me the offer letter, they told they will give it later and whenever i ask them they keep on telling will give later. And at last they told you no need to worry, you just work here and you will get salary on time, if at anytime you want to leave, we will relieve you in 15 Days and will provide you all the documents like offer letter, appointment letter, experience and relieving letter all at a time at the time of exit . I used to get salary on time and so i didnt bother about the documents. Now i got a good oppurtunity in other company and i have resigned my job in current company, now these people are telling me to serve notice period for 1 month and 2 months and now they are telling they dont have any backup for me so i need to refer a guy who can do my work and i need to give knowledge transfer to him and train him all my work and then they will relieve me. As mentioned earlier in the interview by the HR person I have srved 15 days notice and i requested them many times to relieve me as per the 15 days notice. but they are not accepting to relieve me. so, i stopped going to office after completing my 15 days notice period and now they are telling me now they will not give experience and relieving letter, offer letter and also will not give me the salary as i didnt serve the 1 month notice. Now I am unable to join the new company without the documents of my previous company and if i dont join on time in the new company, they will terminate my offer letter and i become a jobless guy because of my old company management. Please let me know how can i get all my documents and salary. please suggest what to do and whom i need to approach.