Agree with other posters. Play hardball with garage. I was told by a well known dealer there would be several months wait on the colour car I wanted. I made a few phone calls and discovered another garage had one in stock in said colour. Told garage I was dealing with that I was taking car from other garage. Guess what! Original garage managed to get me the car I wanted in my chosen colour in less than a week. Reason I stuck with them was that it suited me location wise, but I didn't tell them that. Might be worth while ringing around a few of their competitors to see if they have your car in the colour you want.
In relation to poster who asked why garage can't paint the car, wouldn't this seriiosly devaule it, the colour wouldn't match the colour on the log book, or whatever that's called nowadays