I been banned for 1 year. 1 year ago, I don't know what scamming mean until I read steam guide about scamming. I won't do that again. I accidently remove trade. I have trade waiting and decide to donate Dispenz0r my useless cosmetics. I click accept then message appeared (I don't remember what it said) then I click it. It remove key donate trading. I got very confused and trying to change owner's mind about it. But he banned me. 1 week later, I was very tired of banned and I was not patience, I trading my keys for expensive weapon.
Being banned for scamming keys is a pretty serious offense and can seriously harm the server, I'll have to see what Disp says before I can really make any judgement however.
Also like what Herr said above mod praising and saying you've changed isn't enough to get you unbanned, try making this appeal longer and add more info.