Company is not issuing relieving documents

Hello Sir/Mam, I was working in a company from may 2016, at the time of joining, I signed a 18 months nda with the cheque of 4.5 lakh where the formated nda was on A4 size paper. Then I got an appraisal in june 2017 with a condition where I have to extend the bond for 1 year. Now my current bond will end in nov 2018. Now in march 2018 I applied for the appraisal and got only one discussion with the management in may and the were delaying the process where I have other opportunities too so I resigned from the company there were many reasons of resignation like 1. I do not have my appointment letter on companies letter head it was on a simple A4 size paper i was asking for the same from nov 2017 but always got some xcuses from the management. 2. Offer latter includes 8.30 hours of working excluding half hour lunch, but management wants more hours irrespective of what they offered. 3. Worked 14 to 20 hours in the month of sept oct nov 2017 but got no overtime no compensation, 4. Got no bonus from the company. 5. Always delaying in giving any type of documents. 6. Mental harrasments by all the upper points Now they are making xcuses in issuing the relieving certificates I told them to negotiate on the bond money and they told that they will decrease the bond amount and will let me know about the amount but they are taking so much of time intentionally. The new company wants relieving Documents. So what will I do please help me feeling so depressed and frustrated