Yes - it's just that now, you don't seem to like the value that you just agreed to.
You weren't a Brexit negotiator in the past, by any chance, were you...?
As others have said, pretty much every insurance proposal that I have ever filled in (whether online, over the phone, or with a pen), has had a box for "value" or "current value" on it. If I was insuring a 10 year old Fiesta and I put "£5million" in the box, I'd expect a phone call from them. The default value (in fact online, there's often a drop-down menu when you're filling in the form) is "current market value". If you didn't specify anything different, that's what it would have gone down as.
In the event of a total loss (say, a fire, or something that happens to elderly ICEs quite often
), they would reach for their Glass' Guide, or their CAP "Black Book", and offer you whatever a similar model would cost to replace. So, if it's a (say) 20 year old 5 Series Beamer, they'd look that up and make you an offer based on that. If it's too rare to have an entry, they'd start looking in the Autotrader or maybe some classic car adverts and find a selection of them, and make you an offer based on those. If you don't like it, you can decline that offer and the onus is then on you to provide credible evidence that it was worth more. Some haggling may result and in the end, you agree a price. The dice are loaded against you, of course, because the longer you mess about trying to claim it was worth more, but failing to provide evidence, the longer you have to wait for your payout.This is, of course, academic, because once they find out you fitted a non-genuine cam cover, your insurance will be void and you won't get any kind of payout at all, so it doesn't really matter...
...(at least, so someone once told me...)
If you don't like any of that, you can go to a specialist broker and take out a (real) "agreed value" policy. That's what I have on my old Alfa. There are usually additional forms to fill in, where you give a more detailed description of its condition, and attach photos (they tell you which ones they want, but typically, all 4 sides, interior and engine bay). If it's really valuable, they might send someone round to inspect it, but mostly, they just accept the photos. You are usually limited on the policy if you go down that road though. Sometimes, you have to prove it's a second car, and / or you'll have to agree to a low annual mileage. I couldn't get "business use" on mine, if I wanted an agreed value policy, presumably because few people use classic cars for business miles.
Once you've done that, if the car becomes a total loss, the agreed value is what they will give you. Again, as others have said, the higher the value you agree, the higher the premium is likely to be.
