Just left our car for 2 weeks with ParkingforCruises at Southampton. Process was so easy, from booking, to dropping off the car and then collecting it.
Communication was brilliant with text messages to indicate what I had to do and where to go (but not too many texts which can be annoying, this was spot on)
Person who we dropped and collected car from was friendly and even recommended being vigilant in Cadiz (onw of the cruise stops) as there'd been a number of passengers on the previous cruise who'd been robbed.
Price was very competitive too.
So in summary, good price, good communication, friendly and helpful staff...why look anywhere else?