Relieving letter issue

Hi, I am a Banker.My current employer not issuing my relieving letter.they are telling that my ex to ex-company verification was pending. I worked 1 year in that company. Last day of my working my HR threatened me that he will hold my relieving letter. From last 30 days me and my family members didn’t sleep happily. They provided me my F&F but they hold my relieving letter. I had an issue with My ex to ex company(Kotak Bank), where I opened one group of customer’s accounts and that lead I received from branch operation team. But after few days that customer did fraud. But kotak bank did my background verification and also checked my and my family members account whether I was involved or not. They found that it was not intentionally done. Because of that they provide me my relieving letter and everything thing. But as per policy they asked me to go. And after that same documents I given to my ex-company which was HDFC bank. And I worked there almost 2 years and then left the bank and joined IndusInd bank. But IndusInd bank HR hold my confirmation due to this reason and they allowed me to work for 1 year. And when I put down my paper and on my last working day they threatened me that I am not eligible for Relieving letter. Kindly help me.