That message you received from the Chinese seller to change feedback because they'll lose their job, is a standard one, I've received it a few times too. Just ignore them, it's not true, bordering on harassment they are known to bombard you with these similar messages, leave a fair feedback describing the transaction and let it stand.
As for Buyer Protection Fees ? Many are upset, look for and join in the many discussions on the subject on the forum, many robust discussions !
@bart024