Airtel - Airtel Unauthorised Roaming Charges

I was charged for internet roaming charges, when in fact my phone which is importantly a dual sim Poco F* handset is set to the option - International Roaming as "Never". I wrote to Airtel to their complaint redressal email account ***@Airtel.com and to the nodal officer: nodalofficer.ker@in.airtel.com with no response from either of them. I also filed a complaint through their mobile app ref: **-************* which was arbitrarily closed by them without offering a resolution. The dispute is Rs. ****.* (May to June) + **** (April to May) = ****.** + *** as roaming charges dated June * **** for reaching out to their helpline number while I was on roaming. Total amount = ****/-