But you can charge them for the coffee!  Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

blimey 6.5hrs? i dont know what model you have, but on my bmw 4.4 v8 that would take about 2 hrs max. you have to remove some of the parts to get to others, and them put back the new parts. so really its like just changing the water pump! and then whacking on a new expansion tank, all of four bolts or so. does the mechanic need the rest of the time to go out and play in your rangy, -to evaluate it?

we have a merc clk, when i had an mot fail, on the steering draglink., i bought a whole (genuine) drag link and changed it with just a socket set and jack/stands, took it to kwikfit and tracked it, (£30) job took 3/4 hr, plus another hour at kwickfit, (inc waiting)
perfect,
rang mercedes, later in week, for an estimate, they quoted from labour book, 3.5hrs to change draglink. at £130 hour labour, (2009) £200 for the 4 wheel track, £150 for the part, and then the vat, total, £900

to do the job, its the front wheels off, split 5 balljoints, slide out old, slide in new, -rebolt, refit wheels. track the front, (and back) raise finger as you pass the dealers.
there should be an investigation into how dealers control car repairs, with warranty etc. especially the wages the mechanics, are earning, after dealer manager skims his bit off. i bet they struggle to earn £20 per hour

last time i was in a bmw dealers in battersea london, for fun, i asked about labour, they wanted £90 per 1/2hr!

Out of interest which make of water pump have you bought? Reason I ask is I've just received one today but upon inspection there is a bit of play in the bearings which I wouldn't expect to have been able to feel by hand before its even fitted.

Iam returning it anyway as it looks poorly made and its getting a bit cold outside now to be having to refit it!