the controller didn't even give us a basic service, all we go was "remain vfr in the zone". Maybe they think if you haven't filed a plan you don't deserve a service?
A "zone" is controlled airspace, therefore basic is not available. You will have been under radar control service until you left CAS, at which point you should have been given the choice of ATSOCAS. Quite a few pilots misunderstand this in my experience. When did you go?