Car RC Not Transferred to New Owner

Hello, I exchanged my old car while buying the new one in Gurgaon during the month of October 2019. While exchanging the car, i was given delivery note and few forms were asked to be singed to get the RC transferred. I was given timelines that within 45-60 Days of sale of old vehicle from their side, they will get the RC transferred. In Mid-Jan 2020, NOC was issued from Delhi RTO where my old vehicle was registered to Sirsa, Haryana RTO. But since then, status has not moved ahead. I am constantly pursuing dealer to get this transferred but they are pushing the dates due to COVID reasons these days but are not giving this over email or in writting. Major miss at their side was between NOC issue date (Mid-Jan'2020) and lockdown start date (Last week of March). Now, i am not sure what action shall i take to ensure that any kind of liability doesn't arise in any situation. Whenever i talk to them they just tell me that they are taking it as priority but there is no deadline attached to it. Is it the responsibility of seller to get the RC transferred or it is the buyer's obligation. Please guide.