i had to do this recently, its a pretty simple procedure
firstly get something thin like a flat headed screwdriver and carefully prise off the fog grille, they should just simply pop out, be careful not to harm your paintwork (do it at the bottom where nobody can see if you do make a nick in it)
then undo the screws holding the units on, carefully bring the unit towards you, there should be enough wire to get the unit out with a few inches of room spare, then i think if i remember rightly you just twist the back and it undoes...it'll be obvious when you see it either way! then just install your new bulb and re assemble
i don't get why seat cant say that in the manual, its so damned easy! same goes for my parents a4, it doesn't say
how to change the rear bulbs, when all it is is simply undoing 1 screw and pulling the rear units out? do they assume everybody is incapable of using a screwdriver?