My hair color faded after only three weeks!?

I got my hair dyed from blonde to a medium carmel brown color just about three weeks ago and the color has already faded to almost dark blonde. I use Paul Mitchell shampoo which the salon recommended. I haven't spent too much time in the sun or gone swimming at all since dying my hair. Should I go complain? I don't want to do this because the place has been cutting (not dyeing) my hair since I was a little kid. But I spent a lot of money on getting my hair done and I've dyed my hair quite a few number of times so I know that it's not my hair that can't take the dye or anything.