No personal experience but looking at their website they proudly proclaim -
"We are the ADAS calibration specialists
We calibrate to the manufacturer's required standard."
Interestingly that calibration is not included in their guarantee -
"Our calibration of any advanced driver assistance systems will be true and correct at the time of being performed and will not be the subject of our guarantee."
Presumably once "true and correct" it (the calibration) shouldn't change? I wonder how one checks this "true and correct" calibration before accepting the car back? Can one test drive it to check things such as Lane departure warning is operating as expected? Or can one accept the car but with the proviso one can return if any of the systems malfunction? What time-scale?
As John suggests above get some form of assurance, in writing, before booking the job (which I presume must be done in one of their depots, as opposed to one one's driveway? Another question to ask)