• Positive ratings are earned for trust worthy behavior, it is sometimes given as counter feedback to negative, but when the person who left the negative feedback is still active and on DT, it's not usually done (except majority of people distrust their judgement, in which case they won't last long as DT members).
• The trust system is a user regulated one and the admins rarely intervene.

Your best bet is to wait for replies from the messaged members as they are the only ones who can remove the feedback.