OnePlus - Voucher not received

I visited to OnePlus authorised service center in Bikaner which is situated in modern market opposite D R M office bikaner Rajasthan.I visited there for repairing of my OnePlus * pro phone. The authorised service center person suggested me to pay the repairing cost of Rs *****/- and said they will get me Rs *****/- OnePlus voucher in exchange of my phone. I agreed for it and paid Rs *****/- at the service center by scanning their QR code using UPI to BRV Enterprises it was the name when in UPI app when I made the payment. Then I given them my phone and charging cable separately on ** Aug ****. And OnePlus charging adoptor on my later visit. Then I visited there * * times and called the person Vinod sharma many times for Voucher but I didn't received any voucher yet. He always said that it's stucked somewhere you will get in * days and now it's more than one month I didn't the voucher. I am tired of calling him again and again and it's not possible for me to visit there again and again. I now feel like cheated. That's why I want to file a complaint against the company,service center and the person.