Airtel — sim not working suddenly

I have been using airtel since5 years. Yesterday morning by 10am my sim started showing no service. The sim was working at 8am and later it just started showing no service and i didn’t even take out the sim before that. I tried everything and then contacted the customer care. The person told me that my sim is active from their side and that i might have to get a duplicate sim from the airtel store. One of my friends had a similar problem and he later ported the sim. I am a doctor and i lost my one working day due this issue. I did nothing wrong from my side.