Airtel — My airtel sim stopped working for no reason

Today on 1st Nov 2020, my airtel sim stopped working suddenly without no reason. I tried switching on/off the phone several times but no use. I even used every possible way to get my network detected again but still nothing. I tried reaching airtel through airtel app but they told me that the problem is because the volte setting is off and that I should turned it on so as to use my sim again. Nothing again. Ultimately I switched the handset to check the fault and found that the sim could not be detected on my other handset too. Giving the conclusion that the culprit was the sim itself wasting my precious time the whole time. And therefore I would like to ask airtel the reason why it happened? What was my fault? I had never touched the sim tray and therefore the damage caused by improper sim insertion is ruled out. I even had reset my phone to factory setting. So airtel now I would like to ask one question. Why❓and do I have to again spend money on a duplicate sim for no fault of mine?