Hello Richard,
It's not reasonable that window stay should fail to function, which was the original fault, and becasue of that failure it seems the window has also now detached.
Many caravan windows are designed to be removable (once opened) so perhaps your wife accidentally managed to do that in her struggle to make the faulty stay work. Without being able to see the actual problem or results I can't tell you if the window can simply be rehung or if it has suffered damage to its hinging system. Pictures can often be very helpful.
You don't tell us if you purchased the caravan new or secondhand, If it was second hand then the when was the caravan originally sold?
With regards to the manufacturer's warranty, legally the manufacturer does not have to give a warranty, so the fact they do means they can decide exactly what they will cover and for how long, It generally also includes certain stipulations about what the owner must do to retain the cover of the warranty, for example:- scheduled services, and inspections, and they must be carried out by approved service providers. Failure to comply is a breach with the warranties terms & conditions and can render the warranty void.
If a caravan with any remaining manufacturers warranty is sold, the warranty does not automatically transfer to the new owner. The T&C's will explain if and how any remaining warranty can be transferred or not.
However, every time a
retail sale is made (new or secondhand) in the UK the Consumer Rights Act comes into play. This only affects you and who ever sold you the caravan (not the manufacturer) except where if you used finance then the finance house and the dealer has a joint liability.
For the Consumer Associations Which? web page about the CRA
click here