Reddit and forum threads tend to have more honest feedback than Google reviews since there's less incentive to fake them. Worth cross referencing any shop name across multiple platforms before committing.
Moving cities and losing a trusted mechanic is genuinely stressful. Local BMW owner Facebook groups in Abu Dhabi are usually more reliable for recommendations than random Google reviews since people share real experiences there.
The local off-road crowd recommending a shop for axle work is honestly the most reliable endorsement possible. Those guys push their Jeeps hard and won't send friends somewhere that does sloppy diff work.
Had almost identical symptoms on a B8 A4 last year. Ended up being a worn clutch plate fixed for under 3,500 dirhams. Dealer had quoted similar to yours without even pinpointing the cause.