Were you upset with it after you got it? You should have called then if so. Some haircuts just grow out funny, you know? I have gone back to a hairdresser one week after a bad cut for them to fix it, and I felt so bad telling her that I hated it. FYI, the "fix" that I got sucked, too. Just let it grow out.
I went back to my stylist about three weeks after a totally new cut (6 inches off) and asked her to make a couple changes. I was prepared to pay but she comp'd it. So no, I disagree that you have to say something immediately because you sometimes need a chance to work with it yourself. But six weeks is too long. That is when people are needing a haircut again. Seems like just bucking for a free cut.