Just like to add the following pointer in relation to the link. It states you have to purchase your tickets before getting on the bus from various locatons. We have always purchased our tickets actually on the bus, and you do not have to by a return. Well that at least is the case on the No7 bus, Kontokali to Corfu Town. It is a good service, not necesarily on time, but near enough, and at the frequency according to the time table. It is quite an experience really, specially if you have to stand, hanging off the wrist straps.
Go by bus if you can.