Airtel — Xstream fiber cancelled before installation and refund not received

For Xstream fiber installation I paid 4000 rupees to Airtel and before installing the package I cancelled and I got the message that amount will be refunded in 7 working days.

I cancelled on 28th March and till today I haven't received the refund despite so many mails to the Airtel.

My Airtel Xstream fiber application No is [protected].
New Airtel account [protected].