A very clear consultation will help you to avoid clients not liking what you have done. One that I use is mirroring. After they have explained what they want say "so what I am hearing you say is..... and repeat what it is that they want.
If they are not sure what they want ask them what they do not want(every one knows what they hate few actually know what they want) this way you don't suggests or do what they will not like.
As far as clients stating that it cost more than they expected but they liked it- you are safe! they liked it for goodness sake and to be fair they did not ask! I work in an upscale salon and some of my clients would be mortified if I informed them of the price before hand, and the ones that are not sure ask during the consultation. I my opinion it is the consumers responsibility to ask how much something costs. You buy a shirt you look at the price tag if their isn't one on you ask the sales clerk do yo not?
Next time this happens simply say to the client " Oh, would you like a break down of what I did for you last time? And give her an itemized list of all her services and how much each of them costs, that should solve it right there and she will see what is being charged and probably realize that a lot of it is tax. this way she has it for next time and you are standing your ground never ever apologise for what you charge! they will think you are not worth it.
Would they go into a Chanel store and say wow the jacket I bought last time was to expensive? and even if she did she would receive no discount I am sure. good luck!
patience in one minute of anger can prevent one hundred days of sorrow!