I would try calling them from another number to try and get something out of them.
once you find out who...block the number and post up a free washer dryer on kijiji. remember the person is a night hawk so call late!
edit:have you tried searching facebook? if the person has their cell listed(As many do) and they havent unchecked the box to block that info you may find out who it is.
most people i know have the number listed like : 1234567890 (no spaces or dashes)