You have to go to the profile where you did this "false negative feedback" and than search your feedback and click on "remove" or whatever it says there. Than you can add afterwards another positive feedback.
It's not what I mean. 2 people give me 2 negative feedback without reason. 1 from a kid who star learning to trade, give me 1 neg rep with ridicilous reason, and 2 is from a scammer, he revenge rep me when I -rep him =.=
Go to steamgifts.com then click on Support, then click Ask a Question to open a support ticket
Thanks for advice, I'm opened a ticket to Steamgift support 6 days ago, but I still don't get any response from them :(
apparently they can be pretty slow at replying sometimes. I reported a scammer recently for leaving me negative rep and they removed it and banned the scammer the following day. Perhaps if your support ticket doesn't focus on the fact that there's a scammer on the loose then you could reword it so that it does, so they give it a higher priority.
Oh that problem, I had it too. Someone scammed me and than gaved me bad rep :/ they all trusted him and not me :c
(he has now +0/-1 I have +105/-1)
-.-