how would sir like his duck's ass to look?
I got my hair cut again today, much the same cut as the last time. I have to enquire though, if there's an obliging hairdresser in my meagre audience to answer: do they teach anything at hairdresser school about that tonsorial construct referred to as a cow's lick? Regardless of whether I warn the stylist or not, the inevitable reaction to my spring-loaded fringe is to try and damp it down with water, cut it in a dead straight line, then smear it with "product" in the hope that I won't notice that it's busily doing its own stuff. Hello, I have been dealing with this for 32 years. I know exactly how it behaves, and precisely (to 15 decimal places) how much disregard it has for "product".

I'm not a hairdresser, but ...
I think a useful starting point *might* be to get the same person to cut/style your hairs every time you get them done. Draw their attention to the problem (as you do seem to have done) and on the second and third visits you might then be in a position to open the relevant stage of the conversation by upping the ante a bit by asking them how it can be done better than the last time they did it (where, of course, you use the word "you" when speaking to the relevant person to make clear you see them as having some responsibility on an ongoing basis for what they do to your head).