OK first, the above speaks very poorly of the service shop. We have a problem in the 'States of car mechanics joyriding in customer's high-performance cars, not a short test drive, but long and at full power; This has largely been stopped with said cars having onboard video recording and data recording, and the dealers having to buy back the car at full price. But getting back to you... a test ride on pavement, fine. Returned with mud, the mechanic was joyriding your very expensive bike. About that...

You are running a ridiculously expensive drivetrain, but clearly not a racer. If that's what you want, fine, but yes, cassettes, chain, and chainrings are going to be absolute top dollar. Perfectly functional and still quality drivetrains are available for a small fraction of the cost of what you are currently running. It's the reason I've stayed with 8 and 9 speed rears for so long, parts are dirt cheap, but now even higher-cog cassettes are inexpensive. This makes replacing cassette, chain, and chainring simultaneously a whole lot less expensive. Usually, chainrings are a lot more durable, you can go several cassettes as least with aluminum chainrings. (My steel chainrings are even more durable.)

So I'd reevaluate that service shop, reevaluate your drivetrain parts and possibly downgrade to well-reviewed but cheaper parts. However, purchases online, buyer beware, there are increasingly fake parts being sold in fake packaging. Try to buy from reputable sellers.

I tried to replace my chain after only a few thousand miles, skipped, too late, needed to put the old chain back on and will replace the chain with the cassette. Since doing more standing climbing, higher chain tension, the chain wears faster than spinning up hills in lowest gear, and that changed the tooth spacing on the cogs enough, that a new chain didn't match.

On my old road bike, I was young and clueless about checking chain length/stretch, but was religious about monthly chain (hot-melt) waxing. And I rode a LOT. 16 years later and I notice the rear cogs are a bit cupped with burrs on the thrust side of the teeth. It's only been 75,000 miles. Original chain, cogs, and chainrings. But they were perfectly "worn-in" together. (And most of the mileage was on the flats, and later on mild hills, I always spun up back then.) Upon inspection, chain rollers are mirror smooth but dished like the side of a nuclear cooling tower. Replace chain. Replace crank and rings (2X to 3X conversion for hills). Deburr cogs and simply reverse them, you could do that pre-Hyperglide! Rode great. That bike is in storage but replacing that cassette will be difficult as they no longer make UniGlide cogs (no Hyperglide shift ramps), nor threaded high cog (no cassette lockring), and the 126mm spacing will not fit a Hyperglide freehub body and cassette. I think Sheldon Brown website has some hacks if I ever need.