Are you getting the parts replaced for that?
SLX Mech RRP £60
Deore BB RRP £13
Cheap HS £20
Cassette from £25??
Parts will take most of that out.
1 year use along with milage is not a mountain bike measure it’s for roadies who ride on clean dry roads.
What has she done with the bike? UK based? I’m guessing lots of muddy rides which eat poorly sealed bearings and wear stuff out quicker.
When did you last check the chain length? In bad Uk conditions I was replacing every 3 months to avoid extra cassette wear – chain is disposable item cassette & rings are worth saving.
Lowers service seems to come in around £30-50 depending on where and how far you take it? What fork? Fox should be done every 30hrs and the oil & seals don’t come for free neither does the labour.
Bent mech – well thats just bad luck.
Cables & outers are one of those things, if your changing drive train worth doing to make sure you get that crisp new shifting you just paid for.
As a guess to do all of that would take 3hrs or more depending on what state the bike was in to start with so that needs paying for too.