Ouch...I didn't expect this to blow up so much!
The garage in question was this one
http://www.citybikeservice.co.uk/, you can see the frontpage mentions a "£50 same day MOT service"
They don't do the MOT on site, they do the check then take it to the test site in Bow, 3 miles up the road - so the same person doesn't really do the same checks twice. Also I guess that if the seals/tyre are knackered they charge you the Pre-test fee but you save the £30 MOT fee until after the faults are fixed.
To be honest I can't really be arsed to pursue it any further, it's not worth my time, I'm just happy the bike is on the road for another year ...and still with no advisories.
As mentioned on my first post they ripped apart my rear caliper for £20 allowing
me to rebuild it instead of them and so saving £60...I'm still happy and would take the bike back there as it's 10 mins from work, I'll just make sure that I ask for the charges beforehand in future.
They still should've asked me if I wanted it done though, that goes without saying.