Via Express
http://www.viajes-laurisilva.com/ve-english.htm They don't have an online booking form and as you say clicking on
book here simply opens your mail program so you can send details of your request, however, they are good at not replying and when your forced to phone they say your mail wasn't received. What they forget is an automated reply is generated and if you receive the following then your mail was received i.e.
Thanks for your reservation. In a few days you will receive a confirmation.
Gracias por su reserva. Dentro de un oar de dias recibira una confirmacion.
Danke für ihre Reservierung. Innerhalb der nächsten Tage erhalten sie eine Bestätigung.
Contact-Tel: +34 922 374549 Saying this, having booked the service many times on behalf of others and from feedback they supply an efficient service but a reservation number or some sort of confirmation paperwork should be given for peace of mind at least.
Do ring them if there's no confirmation via email. Oh and prices have risen from those on there webpage so ask exact cost.