Transfer case is whining in my Patrol – anyone know a good shop in Sharjah?

I've got a 2018 Nissan Patrol that I use for everything from the school run to weekend desert trips, and it's been a solid car overall. But recently, I've noticed a whining noise coming from underneath, especially when I'm coasting or decelerating, and it's getting louder by the week. It's accompanied by a slight hesitation when I shift from 2WD to 4WD, which is starting to make me a bit anxious. I took it to a local garage in Dubai, and they just said the fluid looked a bit dark and suggested a flush, but I'm not convinced that's the whole story. A mate who's a mechanic mentioned that if the transfer case is showing signs of wear, a simple fluid change might not cut it, and I could be looking at a rebuild if there's internal damage to the gears or bearings. I live in Sharjah, and I'm trying to find a workshop that actually specializes in these 4x4 drivetrains rather than just a general garage that will guess at the problem. I've been looking into 800Sayara and their services, and I'm hoping to Learn More about the specific process they follow for transfer case diagnostics and repairs. Has anyone here had a similar whining issue with their Patrol and found a reliable specialist in the Sharjah area who actually knows how to rebuild these units properly? I'd really appreciate a recommendation for a place that will do a thorough inspection and not cut any corners, because I rely on this car for the weekends and I can't afford to have it fail in the middle of the desert.