As you know airtel is providing free 1000gb for every new connection. But here is a simple trick to get it for even old users. Just call the customer care and say to them that its a discriminate move by airtel to give 1000gb for new users. Tell them to give this 1000gb data (also known as Big Byte), otherwise you are gonna cancel connection. They will definitely give it to you.
Proof – I got 1000gb yesterday