So are you saying the text you type and post is read by a human who decides to censor the feedback? or was the option to rate the seller with a thumbs down not present in the GUI?
I tried giving the negative feedback repeatedly for a couple of days. It is like trying to book a train ticket during peak season. I hope you are getting the analogy. You select the train, feed the passenger details, your credit card details and in the end, when the transaction is supposed to take place, the screen goes blank or some error code is displayed.
Each of these cycles is so time consuming and labour intensive that you get frustrated in doing it repeatedly.
After a few days, (3 days I guess) I realised the futility and left it.