Fot the Mexican bus system, go to
www.ticketbus.com.mx, there is an English version, sort of - the Spanish version is not too difficult to follow.
From Corazol to Chetumal, and vice versa, George Morales will take you across the border - these drivers know all the border people and are a great help. His e-mail is
[email protected]His tel. number is 501-4222485, or was the last time I spoke to him last year.