2bh Monaco is a problem colour in our experiences.......alot of clios arent factory original, theres also the odd, friday after noon car floating around lol. I tried all IXELL shades against my own monaco clio years ago and not one was even close, also all the shades are country mile off from each other, same as Iceburg silver, thats also a right arse. When someone's already balls'd up the match on a 1/4 or something, those are the worst.
If your joining line to line (i.e spoiler to roof) , 9.9 out of 10 times, you'll have to blend if you want it too appear spot on. I suspect in this case it must have been a country mile off mind you......sample cards are must thats for sure.