Sometimes when jacked up the vehicle will show a message saying reset the suspension (can't remember the exact wording). A simple height adjustment is all that is needed. If they lowered it to access height and then, once work was done, drove it out of the bay a bit sharpish, the height would have risen unbidden. That would remove the "error" message.

Sounds like the chap just didn't know the car or its systems.

Interestingly, Halfords wouldn't fit a battery for me (I was at work and had bought it when my alternator died). They checked their list of allowed cars and it said "no". I guess it's because you have to let everything go to sleep before disconnecting the battery. I wonder if they've had to pay out for issues in the past. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed