My Ex Employer not providing or contacting me for any exit formalities or letters

I joined Gebbs Healthcare Solutions Airoli on October 2019. Everything was going fine until lockdown. So we were given Work from home but the particular client of the project discontinued 30 July 2020 and we were On No work No pay. However i get the call on 10th August that i have been assigned to a new project but in different location that is andheri. We are given traning from 11th august 2020 to 15th of august 2020. I clear my tranings but i never get to work as my login id never get created. So in October 2020 i decide to look for a new job and resigned on 3rd October 2020 and also infrom my team leader and the resignation is also approved on 5th october 2020. With date of separation of in next 30 days. All these months i was on No Work No Pay. However after approval i never get any call or email for exit formalities. So i contact the HR and enquire the same. HR just keeps telling me to tell you TL to contact him which i did and he say ok i have done. But no progress.Its april 2021 my current employer demands experience letter for back ground verification. So again i contact the HR and he says me the same thing again to tell my ex TL to contact him. And now the TL says to HR that i was never reporting him. So how can i have a letter which has approved resignation with his name on it. I keep trying to contact them but none of the person i giving me replies. What should i do because of this mess i am set to loose my new employment. I am in a very big trouble but my Ex employer is messing my life completely up.