I really do think that is absolutely disgraceful. It used to be part of the attraction of the bespoke cars that you could change the specification at any time up until the car went into build.
I made several changes before the final spec and was not charged the so called "Specification change admin fee". At the most it costs them 5 minutes to change the spec in the computer system. Let's be generous and say 10 minutes to read the (e)mail and enter the change. That makes a fee of £3,000 and hour. I wish I could get that.