Cocks and dog bastards. Tell them to pay up front. And if they don't like anime style, the door is there.
You have a skill that is worth money and time. If they aren't willing to give you those when they request it then it isn't a job, it's slave labor.
@Prince_Azmiran_Myrian well, I have no plans in having myself promoted, because I want to stay on the field, teaching rather sitting and rotting in an office.