I wouldn’t expect a well ridden alluminium frame to last more than 5 years. Steel and Ti longer but nothing lasts forever.
A mate had a 7 year old Marin FS frame replaced with no qibbles but it was an old stock frame and not a current model, but still newer than the one it replaced.
I think Orange are a bit tight with their frames out of warranty and only offering a % off the full RRP of a replacement.