I have encountered this problems 4 times before with the same learner. Long Story short I help them with a topic and than they give me an Unhelpful Rating. I am a type of person who can get demotivated with these rating. Unhelping Rating with an EXPLANATION may help tutors learn from their mistakes and see what can change. If I am getting these Unhelpful Rating with no feedback, not only does it make me demotivated, but it also does not help me know where I can improve.
My Final suggestion is If a person selects Not Helpful Rating, can we add a tool where they have to type out why it wasn't helpful.