Well... After years using trademe.co.nz I think I now have got evidence they hit the point where the only thing you can get out of their "Customer Service" is a canned reply:

"Unfortunately unless feedback breaches Trade Me's feedback policy Trade Me will not enter into feedback disputes.

You may wish to approach the trader that placed the feedback and come to an agreement regarding the feedback."

I had an item for sale and someone hit the "Buy Now" button. Immediatelly after the "buyer" sent me an email, first complaining about the shipping fee ($20 for a relatively large item) and then asking if it was possible for her to pay in two consecutive weeks (this is for a $150 item!).

When I said "sorry, but this is non-negotiable, she offered to pay 100% the week after, and I agreed. Seven days later she sent me an email saying that the deposit was made, and please send the item to [address].

Of course I did not send the item, and guess what? The money wasn't deposited (surprise!). Two weeks later, I used the Trademe mechanism to cancel the auction and get a refund of the success fee. An of course posted a negative feedback on this person, saying that she did not complete the transaction, delayed the replies and promised to deposit the money but not doing it.

Next thing I know this person puts a negative feedback on me, clearly as a retaliation. The feedback simply sad I was grumpy. Not without reason, sure?

The problem is that regardless of being retaliation, non-realistic or whatever, the feedback counts as a negative point in my profile.

The trademe response to my request to have this (obviously non-realistic) negative feedback removed was the canned reply above - twice!

That's it. Enough giving money to Trademe. I rather give away things to someone who needs them, than use Trademe.