Sadly @DavidR, you have been mislead.
However - just to add some context.
What you and I might call the 'bumper' dealers have a different name for, (bumper cover or valance i think)
In dealer terms the 'bumper' is the metal structural comonent which provide crash (bump) protection underneath the plastic bit which we all refer to with the term.
Now, in order to remove the "metal bumper" it is indeed necessary to drop the exhaust out of the hangers (which are part of the bumper)
I can confirm that this is a PITA job, 4 hours would seem a bit of a strech however.
In oder to change/replace your fogs it is absolutly NOT necessary to remove the "bumper", only the "bumper cover". To do so the general process would be:
remove both upper light clusters - 1 bolt each,
remove lower bumper cover (which covers your spare wheel/tow eye depending on config) - upto 4 screws
remove bumper cover - 4 bolts underneath, 2 bolts each side.
Carefully peel bumper away from car and disconnect wiring for fogs/sensors.
replace fogs (must confess, no idea how many fixing for this)
I'm not a mechanic but I have done all of the above work fitting my towbar -
I could easily do all of this, change the lights and refit in 30-40 minutes.
What i bet has happened is this:
The mechanic who worked on your car says: "i finished davids car, can you bill him for the fogs, and the book time to remove and refit the bumper"
The mechanic gives the service manager too much credit, and assumes that the service manager "knows" he means the bumper cover, not the metal bumper, however the service manager is a moron.
Instead of charging you the book time to replace the bumper cover (which is what it should have been) you have been charged the book time to remove the metal bumper - which includes the cover, and the exhaust.
I would call them up - tell them that they made an honest mistake, and whoever compiled the invoice selected the wrong work item.
Give them the chance to rectify it, and realise that the idiot who spoke to you before did not understand the job - ask to speak to the tech who did the work, ask him if he actually had to remove the metal bumper.
MY17 SE-Tech 180 Manual 7 Seats + Spare. TSR, Reverse Cam, Privacy Glass, Santorini Black roof.