False allegations in releiving letter

I worked with Zumi Solutions Pvt Ltd from July 2019 till May 2021. The company has recruited me with a 3 years employment bond but have not provided the copy of the bond to the me. I was forced to work during lock down and did not offer work from home. I was infected with covid19 also. As the management was continuously refusing to give work from home and I did not have any project work. So, I decided to resign and sent resignation letter 11 th May 2020. I was ready to pay the compensation for breaking the 3 years agreement. The management immediately blocked the mail id, company login ids etc. and did not give any response on the resignation. While I contacted the management on [deleted] through the union Forum for IT and ITES Employees, Mr.Zaid, from Zumi management, they did not raise the notice period issue. They kept some false allegations like the I published customer project details in the Linked In media and customer has sent a notice to the management to pay huge fine amount. When the union FITE asked for copy of the notice, the management did not send instead they said they will give the relieving letter and experience letter. But now, they have given a bad feedback in the relieving letter that I exited the company without serving notice period and without giving knowledge transfer. This is very much clear that the management has taken a revenge against me and wanted to give trouble in getting new job opportunities since the I am breaking the 3 years bond. .