Balfe's are a Windrush partner, but (or perhaps more so) I feel I ought to share this story. The lesson is, at the least, that it's often prudent to collect a second opinion.
I booked my bike in to fix a bashed brake cable 'collar' (the silver bit on top of the caliper) and get the gears spot on again after the bike was bashed being transported (slung in back of an Uber after two punctures in a row in the pouring rain). I opted for a service too, and dropped my bike off at Balfe's in Dulwich.
The mechanic called me reporting £400 essential work for my bike to function. This included telling me that the back wheel was bashed oval, 'egged', and needed replacing or the gears would never work. I agonised with him over whether a four-year old bike bought for not much more was worth the cost. I missed a sprint tri, and was facing missing the Dun Run this weekend.
You can guess what the main course of this story is... but first, here's the starter - I picked it up a week later (to possibly sell it for parts or a project). Well, the guy was so patronising that I'll not set foot it there again. I span the wheel and said, 'oh, there's not much movement' (at this point I genuinely didn't doubt the diagnosis) even so, I got a passive aggressive talking down:
"The thing about bike wheels is that they're supposed to be ROUND"
"Ok, gotcha. I'm just saying it's not that bad, not as much movement as I expected."
"The thing about bike WHEELS is that they're SUPPOSED to be ROUND"
"Okayyyyyy…. anyway, I was wondering if the gears..."
(Cutting me off)"The thing about gears is if you ride the bike in the lowest gear on the chainring and the highest on the cassette the chain will be diagonal and it won't run smooth"
"Errr… yes. (I pause, the guy is just glaring at me). I actually do know that. It just that your mechanic said the problem was..."
(Cuts me off again) "The thing about GEARS is if you ride the bike in the LOWEST gear on the chainring and the HIGHEST on the cassette the CHAIN will be at DIAGONAL and it WON'T run smooth"
I paid for the brake cable which I'd asked them to still fix. Which he said was £5 more than the mechanic had said when he called to say it was done. He rolled his eyes "Fine, right whatever". I paid and left.
After my bike had laid around for another week, out of sheer annoyance I attempted to fix the rear derailleur myself… it ran fine. The chainring alluded me and I popped into Bon Velo. They adjusted the chainring on the spot for free and the bike was running as well as it ever had. The Bin Velo guy did mention to me "you might want to replace the chain and cassette in the next few months" I showed them the back wheel movement, "There's not much movement. (My exact words in Balfe's) It will probably disappear if you get the wheel trued"
I took it to another bike shop after that and they gave me exactly the same advice. Both quoted £60-70 just to replace an 80% worn chain and cassette. The gears were fine, the wheel was fine - less than a millimeter movement.
I called and raised it with the Balfe's manager. He apologised for the guys behaviour. I've not had an explanation about the quote for £400 essential work.
Incedentally, Balfe's in Streatham have fixed some broken spokes for me before and were fine, and charming too.