Oh, that's a tough one. I had to deal with the same thing when I stopped seeing the stylist I'd been going to for several years because her level of service had really gone downhill, plus she was a straightening kind of girl so she didn't want to help when I went wavy. But I didn't want to hurt her feelings, just the same.
What I ended up doing was to use one of her service issues that had nothing to do with her skills, which was how hard it had become to get an appointment with her (instead of how she wasn't highlighting the back of my head like I was paying for
), and I turned it around on myself. I said there were some changes in my life recently and I just really needed more flexibility than that for a while when scheduling appointments. It was quite true, it just wasn't the whole - or main - truth.
Is there anything else that could be a valid reason that has nothing to do with her personally, that you'd feel comfortable using - like that you need something closer to work for convenience because you're working longer hours lately, or the economy is killing you and you need to "take a break" from her prices for a while, or something like that?