I'd had Petplan for years but I fell foul of their semantics five years ago, when I got my rescued Rommie.
His passport says "Crossbreed", which I entered, but then I had to specify which breeds were crossed. No idea, so I rang but was told I needed to specify or guess what he most looked like. I explained he was a mongrel but they wouldn't accept that category because the passport said crossbreed.
I suppose I can understand the semantics but to me as a lay person the two names are interchangeable. If I'd just decided to put "mongrel" on the form, any claim would have been disallowed, presumably.
With Animal Friends now. Haven't needed them yet but at least the telephonic registration was in normal language.