Airtel — Sim card defective

Address:

AP

From morning, my airtel sim network has gone and no mobile is detecting the sim card. Have called to airtel customer care to help me replace it with a working one, for that they asking me to pay for and get a duplicate sim card by visiting their store. If there is some damage with sim card is airtel is not responsible for it. If this is case why we are paying monthly as a recharge if airtel is not taking care of such small thing. I need proper response for this.