Full & Final Not Received From My Previous Company

I have worked with 1 company and since 05-10-2017 to 14-06-2018 company Mind up offline Filed Emp but as per Agreement between me and employer is if I left or company mindup me they will clearly my F&F and as per 60 days Conditions is completed In 14-08-2018 and still I have not received my F&F and other clearance certificate from my Previous Company. I have already sent 2 Legal Notice 2nd one is recently sent to my Previous company but still not received any Reply from my Previous Company. Please Suggest me what next step I can take .I have all Documents