Hello Antony and Dee,
Welcome to the forum.
Have not come across that problem before but if you or any other member has a PDF of the owners handbook or indeed a schematic of the electrics, I wouldn’t mind a look.
Is it under warranty ?
Is there a manufacturers name on the charger, for instance CBE or Toptronic and where is it situated ?
If all else fails, try and get to Prestatyn in April and I will do some tests.
Don’t rush into spending a fortune at a dealers.
I note you are in Teignmouth. Steve and Maureen who have a similar van will be at Dawlish mid March.