need relieving letter

Dear Sir Very Happy Good Evening. My name is Satya Prakash Pandey I worked in a Airtel Gurgaon through the payroll of little company named MERCURIOUS ADVISORY SERVICED PVT LIMITED situated in Rohini Delhi. I worked from June 2015 till October 2015. As per their appointment letter there is 1 month notice period. I resigned on 20th Oct and leave on 30th October. I didn't received my salary for the October month and relieving letter My current employer is asking for relieving letter forcely. Now I am requesting for relieving letter. Inspite of repeated attempts I am not getting any reply from their side. When I called him, he completely declined the request. If I will not get my relieving letter I will loose my job. One more thing , in appointment letter it is mentioned that 6 month will be on probation period. So I was in probation period at that time when I resigned. Please sugget , How I will get my relieving letter. What should I say to my current employer. Is there any legal process. I am in too stress. My mobile number 8860494155 Please suggest. Will be grateful to you