You said the
battery read 13.25v after being disconnected for a few hours, did you mean disconnected from the charger? if so and whatever you're using to measure the voltage is reasonably accurate then the
battery was indeed fully charged. The most likely culprit for draining a good
battery in a few hours would be the fridge, normally that would auto disconnect from the 12V source when the engine isn't running so for the fridge to drain the
battery while you were static the fridge relay would have to have welded it's self shut AND you'd have to have left the fridge set to
battery, highly unlikely?
From what you've posted it seems you gave it a really good charge and then it didn't last long running very little, on the face of it that's a knackered
battery BUT it seems strange that a lead carbon should fail after such a short time. If it has then you've certainly got a claim under warranty.
So, was that 13.25V while the
battery was still charging or while it was resting?
How did you measure 13.25V?
Did you definitely turn the fridge
off 12V when you parked up?
How many hours do you think the
battery lasted while parked up?
Do you have any other high load appliances such as an
inverter?
AND the most important question......why on earth are you camping in Leicester?
(I can say that cos I live there
)