Need help with wiring harness install on 2017

Any info or DIY on installing wiring harness on 17 q3? Did the hitch but nobody wants to do wiring for me in town, they say to go to dealer for a kit but dealer says there isn't one available. Uhaul only place that says they can do it but when I asked them certain questions bout install they said they would need to watch the video on how to install it and the installers seemed like kids who didnt even know what they were doing so not to confident getting it done there. Any help or recommendations on kits would be appreciated. thanks