The following are a list of a selection of company websites in the Lisbon area offering bus charter services:
WH-Executive Service
http://www.wh-executiveservice.com/autocarros.php
Rodotejo
http://www.rodotejo.pt/informacoes/alugueres
Polibus
http://www.polibus.pt/index1.php
Carris
http://www.carris.pt/en/useful-contacts/
Diana Tours
http://www.dianatours.pt/pt/index.php?doc=autocarros
Be aware that while some of them will speak English, some may not.
