Airtel — Denied providing service and didn't return the paid amount

I booked Airtel fiber connection and was told by the sales person that I would receive the connection within the next day and that was my very condition for booking the service. After getting permission from my society and the confirmation amount(message attached), they told me that it would take a week because the area is not currently fiber serviceable . Since I'm not an Airtel telecom customer, I can't call their complain number - 121. I have tried using their app for cancelling and have asked the person in contact to cancel it a lot of times. They mentioned that they have cancelled it but it's been two weeks and I've not received confirmation for the same. The salesman has also stopped receiving my calls.