Hi JohnyB
Its very difficult to diagnose some problems through a forum, as some diagnostics may be required to correctly identify the problem. If your caravan is new or recently purchased, it might be worth contacting your seller.
However, I have come across strange electrical behaviour previously in older caravans, but of course there's no certainty your caravan has the same problem, but.... A caravanner was using his caravan at home on mains power, He had removed the leisure battery as he didn't think it was needed. If fact the caravans charger did need a battery to help smooth the current from the charger, and without the battery the 12V supply was rippling with big enough dips to cause his space and water heaters systems to think someone was turning them on and off 100 times a second (twice mains frequency due to the full wave rectifier in the charger).
But having checked out the Pegasus Verona It seems it's unlikely to be that old as newer caravans do have fully rectified and smoothed power supplies.
Most likely somethings faulty and it may need a caravan tech to investigate.