I have been working with this service for over 5 years now in different roles within my organization as well outside work related duties during times when no one was available to answer phone calls or send emails back (during holidays etc).
They're always reliable but sometimes it would be better if they could do more proactive training than reactive trainings whenever there's something new that has come up since their last update/training session; however nothing serious about these issues so far from what i've experienced myself while being trained by them at least once every quarter year until today!