Company is not willing to provide experience letter.

Hi Recently I have joined in a company. From my last employer I didn't receive any releasing letter or experience certificate. As per my offer letter I have completed my 90 days notice period. Before my last working day they are saying that my work is not completed hence they will not be providing those documents. They didn't provide my salary also. When I have sent the resignation email they did not accept first of all. In this current situation I was working from home an d they forced me to come to office. I used to come and do the necessary tasks which was assigned to me. They were continuously assigning new task in my notice period. I used to complete all of those. Before three weeks of my last working day they assigned a task to me which I had informed earlier to my reporting manager that this task will not complete in this duration. They have assigned the task via the same resignation email without any discussion. I have informed several times that I will be contributing till my last working day verbally and they agreed. Now after completing my notice period they are not replying anymore. Hence which step should I take to get my documents.