Is there any protocol or system for organizations to give feed back about volunteers? We have had thousands of wonderful experiences with volunteers but there have been one or two unpleasant incidents. Is it possible to request that a volunteer not be placed with us again? Or to provide them with feedback on their behavior via VCI? What do you tell less than exemplary volunteers?

There's no protocol that I know of, I'm sure you could send an e-mail or contact your local VC directly and let them know.

Maybe you could try talking to them one on one first. If that doesn't work, your volunteer centre will be able to provide you with some insight as to what to do.