my wife will set a task to be done by our sons. which upon completion will get a reward. But when the job is done she asks them to do more before the reward comes.
My wife is totally unwilling to discuss the situation.
So the sons are very upset with her. This has gone on for several years.
There is little in this life that is reliable. But 'my word is my bond' should work. And if something does not work then at least being able to have a discussion is necessary where at least each persons view is heard, and then each person could reflect on the situation. And in time a change happens.