Boat — Not get my product but on delivery status it is written that it has been delivered

My boat rockerz 400 was not working properly. It was in warranty so I decided to register a complaint.
I registered my complaint on 1st august and a person came and picked it on the 4th of August. It was written in tracking details that I will get my headset back by the 9th of August, but I didn't get that day. I thought that it may be because of COVID-19, and left it. But when I checked the delivery status after a few days, it was written that the product has been delivered, but I haven't received it. I didn't even get the message that the product has been delivered because before any delivery it is notified to the customer that you will get your product delivered today but I didn't seven received that message.

So, it is a request to please check it. I called on customer care number but I did not get any reply and on mail also I got the ticket number issued but no response has been given on it.

Please help me out. I want my product back.