HSMP extension to Tier-1: anyone applied in person at Croydon?

Read from the application form, it is possible to do so at a price of 1,020 pounds for the main applicant.

However, there is a link at UK Border Agency still saying "you can not extend your HSMP visa in Croydon office" - is it because they didn't update the content accordingly, or because HSMP is still an exception?

Anyone has got first-hand experience?

Thank you very much.