I can't send an email to ASUS as they require a serial number which is not on the product that I have.
I can't call them as I am unable to find a phone number anywhere.
My nearest ASUS service center is unable to help as they only deal with laptop repairs, so I'm trying here instead.

Product in question: https://www.asus.com/us/Headphones-Headsets/ROG-Strix-Wireless/

As the title says, I don't have a USB dongle as it got lost when I moved houses. I checked everywhere, it's not there.
I'm willing to pay for it if I need to, I just want to be able to use my headset as surround instead of stereo with the AUX cable.

Can you help with that? I live in New Zealand.
Cheers!