Transfer Of Mahanagar Gas PNG Connection

We live in a flat in Thane that was owned by my father. He passed away last year and as per the nomination, the flat was transferred to my mother's name. My mother would like to transfer the Mahanagar gas PNG connection from my father's name to my name since I am also a resident of the flat and will be paying the bill. Mahanagar gas has refused this transfer citing that my name is not on the share certificate, even though my mother has written a NOC for the transfer to my name. They have asked me to provide a NOC from the society instead. The society has outright refused to provide a NOC, citing the same reason (my name is not on the share certificate and not a member of the society). My questions: 1. is Mahanagar gas justified in asking for the society NOC, given that my mother who is the flat owner has already provided one. 2. can the society legally refuse to provide the NOC to me, even though my mother has asked in writing. 3. how should I approach this situation.