Owning your own home

I've seen another one where the freeholder states the new ground rent as a proportion of market value and the leaseholder has threee months to challenge it. What happens if the leaseholder goes travelling for four months and comes back to find the freeholder calculated it at £20k per annum and the leaseholder has missed the deadline to challenge it?

You can easily see stuff like this being a misselling case in the future. It's obvious that people just want somewhere to live with a known cost into the future, yet are being sold complex (index linked!) financial instruments tied to their houses.