Visitor visa extension second time

[Snoov]

Hi, I applied visitor visa extension for my parents in July. I requested an extension until Nov 25 but our plans have changed, and they are traveling back on Dec 15. Today I received an email saying there is an update on the application. It only says the final decision has been made and they have requested a medical examination for both my parents. Document status expires on Nov 19. Does this mean their extension was only approved until Nov 19th? Can I apply again to be extended to Dec 15?