Bharti Airtel — change of defective sim card

Address:

Tuli, Dist. Mokokchung, Nagaland

My wife bought a new Airtel sim card in 2018 and it's having some problems like; not reachable most of the times and 'error in application' keeps appearing on the screen. Visited the above mentioned store for replacement of sim card but we were asked to pay Rs.150/-. Was willing to pay the amount but again asked to provide voter's ID card, was carrying only Aadhar card at that time. So couldn't get the sim replaced, is voter ID card the only mandatory document for a sim card? 'cos we were told to submit none other than the voter ID card only. Is Rs.150 for replacing a defective sim card justified?