Earlier quoted context omitted.
Pretty sure if you go through the effort to challenge such charges you can get them changed. https://www.vox.com/2019/3/22/18261698/how-to-fight-expensiv...
The thing I don't understand about tips like these is, what obligation does the other party have to cooperate at all? Like you "ask for a supervisor" (and then a director!) what incentive do they have to not just say no? Or if you ask for an itemized bill, what if they just refuse? How are you supposed to get past a blunt refusal, which to me seems like the easiest response for them?
See also the US unemployment benefits situation, where many employers will contest an unemployment insurance claim by default even when the worker is actually eligible, in the hopes that some workers will not navigate the bureaucracy well enough to fight back. Because of the weakness of their case, however, they will then back down as soon as their denial is challenged.