Airtel — Sim card showing no service and no network

It's been 1 month now, and none of the airtel staff are responding to the issue that me and husband is having. On 28th of July our both Airtel Sim have stopped receiving OTPs and text messages even though we have recharged and the validity is still there. Reached out to regional managers, customer service but no solution. They dropped a mail asking many questions and steps to follow which we already did and told them. But there was no response or solution till date. I really want to sue them in consumer court because of the trouble they are causing us during this Pandemic and being abroad.