For those of you who haven't tried it, there's a feedback system on mtvan.
You can only leave feedback if a job has been posted on the system and allocated to the courier doing the job.
The feedback is only visible (ie on the member's Profile) once both sides have left feedback.
The Vendor (ie usually the courier company) selling the job sees this:
The Courier (ie the person or company doing the job) sees a slightly different page:
Please don't leave feedback until you have been paid!