False statements to background verification team by past employer

I got selected in MNC and they offer me a Job and they started the background verification then one day one of my past employer gave them false statements about me that i left the company without informing them and did not complete exit formalities. As the proof i have screen shot of resignation mail and also the relieving letter and the PF’s exit date is matching with my relieve letter’s date that completely denies accusations. Now past employer not responding my emails with any sort of proof.