Airtel — Damaged sim Card replacement

Address: Airtel showroom, Saligramam, chennai-600092

I have upgraded my aircel sim to Airtel Postpaid later changed into prepaid on 2018. In 2019, tower was not shown in my mobile even after restarting my mobile. When I enquired in showroom, they said sim card might be damaged. So I have paid 25Rs and replaced my sim card. Same issue occurred to me on[protected]. After enquiring, showroom staff told me, they are not manufacturing chip/processor.i have again paid Rs 30 which I asked Bill, but showroom declined to provide any bills.