Airtel — Airtel xstream fiber

I am HariPreethi, staying at Chennai, we took a connection of Airtel Xstream fiber on July 20th 2021, Sales executive named MR.SENTHIL of Airtel has given us connection on JULY 20th 2021, and made me pay amount of 1500RS for Xstream fiber box which is refundable(saying when we surrender the box we will receive paid amount 1500RS as a refund).MR.SENTHIL made me pay amount through google pay to the contact named MR.MANIKANDAN(Jilla Mani is the name present in google pay).And now we are vacating the house so wanted to surrender the Airtel Xstream Fiber box.these people are saying now its non-refundable.