+1 Michael, just used them to MOT my car. They're very helpful. First time in ages I've passed without needing a bulb or some other minor problem. Haringey closed some time ago.
Not in Harringay/Haringey but I use Car Care Centre on Maury Road, N16. John there is very friendly and they do a no frills, no messing service and what's needed. I have been going to them for around 8 years and with two different cars. 020 8985 2983 - like others, it can take a while for them to answer as they usually have their heads under a car!
I can recommend the garage on Wightman Road near the top of Fairfax / Falkland Road. Can't remember what they are called but the number is 02083477111 and they have a Bosch sign on the front.
They have serviced and done MOT on my 8 year old VW the last 4 years. Friendly and helpful.
I went there with a horrific grinding noise from my brakes last month. No appointment. The guy looked at it there and then, took off the wheel and found a trapped stone in a brake caliper. Removed it straight away, no charge when I had gone in fearing the worst.