Buy a new one from a retailer that has screwed you around in the past, take it home, put your broken one in the packaging and return it for a refund because you don't like it, it's broken, whatever.
They will get stuck doing the paperwork shipping it back to MS, you will have a measure of revenge, and MS will end up replacing the mouse which is what they would have done under an RMA anyway. Everyone is happy except the retailer, but he deserves it for having jerked your chain before. If there is no retailer that deserves your wrath, have fun with the MS phone menus...