Grief is grief, regardless of its value. If it wasn't so valuable to you, why did you break it in the first place?
There is a rule when you enter the game at the spawn and it is in /rules, that specifically states no griefing. We take grief very seriously on this server and the amount you grief helps mods determine your ban time. A mod can choose whatever ban time he/she sees fit. It's best you wait it out and don't complain. In the meantime, play another game, read a book, or go outside until the ban is over.