Quoted from Yesh23:I took Bud's advices and went on the feedback section and put a recommendation (about my negative interaction with the Pinsider) and submitted but come to find out, you can only give positive feedback this way, am I doing something wrong!
It looks like you can only write unsolicited positive recommendations.
If a seller chooses to request feedback when ending an ad, then a buyer can submit either positive or negative feedback.