If the dispute window has passed, you can post on vendors page. I'm not sure about the exact requirements, but it's something to the effect of: post title says ' request late dispute ', and inside main message, you leave the order number, date of purchase and reason for dispute.

It’s after 9 days from being sent that the dispute button appears

Where does it appear as today is the first day I can raise a despite, but there is still no button appeared