Airtel — airtel charged me rs 600 for 2 days. unable to reach airtel representative. unable to make calls to 1800 number

I tried using airtel 121/198 and airtel thanks app but it does not allow me to get to a live agent. I bought an airtel prepaid sim 2 days back and paid rs 350. The same day it showed insufficient balance and i recharged again rs 250. It still said low balance so i submitted a request to convert to postpaid. Airtel is saying that the rs 350 + rs 250 = rs 600 i paid is gone. This is fraud and stealing. I tried calling customer support multiple times but not able to reach a representative. On top of that it does not allow me to call any toll free number (1800/1866)