[Johnnyboy]

Seems they let the batteries run down. I would check your batteries for age, maybe they need replaced anyway, sometimes it’s good to have a fresh start on batteries. If the batteries are not to old I would try to jump the batteries enough to get the generator running and put a big battery charger on those batteries.

 I have had the same issues before from shops. Been my experience, they will push off coach work and work on bigger clients fleets etc. before they get to your coach, not always the norm. 

My only success is to visit every day or very regularly to get them to start working on it. This is not a big job, usually done in a day easily.