You know – it’s going to be sad if someone doubts you after you’ve tried your best and even put in the best thoughts for him or her.
People who are older or more experienced or successful would definitely advise you to persist on. But does it worth to waste your time on someone who doesn’t even have the patience to listen to you? It’s best to keep quiet if you don’t have power to overcome a group of people who are so united when their deeds are being untold, or if you’re just too kind to let them have their retribution. Just shut up.
When people often ask you to speak up, say nothing you think need to redress. Everyone just expects sweet talks; at least in their minds they hope you’ll say only something nice.