Airtel — Do I need to do Document verification every once in a while?

Last year only i was bar of network and call and was asked to submit verification so i did it. Even my existing validity was not valid anymore and I need to recharge it again.And just yesterday i was bar for call again an when I ask the customer support they told me I need to submit my verification again.And when I ask Do I need to this every year? They can give me no answer and keep repeating that i need to submit document in the nearest airtel store. Don't know whether I will need to keep on submitting documents every once in a while.