The guys charge a straight £50 cash - I'd rather pay the extra than get it failed by a garage looking for work then having to retest elsewhere. Many years ago, I had a car fail at a normal garage because 'the brake pads are wearing low'. I asked if they passed the brake test, which they did, but his reply was that it was a safety concern as, in his opinion, they would wear out before the next MoT. I could smell the bull^&%&, but there wasn't a lot I could do. I paid the fee, took the car elsewhere, and it passed no problem.
I know a lot about MoT testing as I've read up on what is testable and what the requirements are. Like with brakes, if they perform as they should, then thickness of pads is simply an advisory. I've even heard of pre March 2018 cars failing on DRLs not working when they weren't even testable until that date.
Pity more testers weren't like Rog