Don't tell 1000 times

If you want to give feedback to anyone, tell him/her once or twice. You can give one or two examples on that for better clarity. If that person asks for more specific information, then you can give all the details that he/she has asked. For any sane person, telling 2-3 times is enough. If that person does not listen, then you can tell the same after few months. If that person does not listen even after that, then you can proceed as if he/she is never going to listen.

But, without asking if you are giving one example everyday for a month, or 20 examples in one day, you are just breaking the relationship. Never ever think that, it would be good for that person by providing more feedback. It just breaks everything.