I'm in Kent; and the price was more or less what everybody else was quoting around here, and I'm assured it will not affect vehicle warranty.
The installation is a 3-4 hour job (even by experienced fitters) and involves taking off the rear bumper and under tray, replacing the crash rail, cutting a slot in the under tray and refitting.
Removeable towbar was not much more than the fixed, and means it can be taken off if it interferes with the rear parking sensors, or my shins!
Vehicle specific wiring at £158 was a fair (?) chunk of the price......