Yes, it's not a renewal of the visa, but my previous lazy shorthand can in no way be taken as advice to others that a visa can be extended. They should always seek proper advice, not rely on a post in a forum by someone they don't even know, otherwise they deserve everything coming to them. Good grief. That applies to any online open forums, including 'latest expat tax advice' and the rest.
As an example I never even leave the country without rechecking the latest regulations on re-entry in case they have changed since the last time I left (usually a matter of years). Ignorance is no excuse.