Another patch maintenance, another person whining about said maintenance. SE posted the time and date for 3.1 ages ago as Hyouretsuzan stated - it's up to you to actually take proper notice of it and read it carefully. This patch is adding a whole new area to the game so that alone explains the longer downtime.

Besides, if you're so narky about this situation, refer to the Terms of Service you agreed to when you signed up for the game - amongst other things it states that they reserve the right to take the game down for maintenance at any time without warning or compensation to you the player. Legally, SE are under no obligation to even tell you when they're taking it down.