issue with common share expenses for commercial property

myself and the other tenants in my building are having an issue about common share expenses. We were recently presented with a 12k bill for painting the outside of the building. We were not informed about the painting prior to the day it started, the lease is a bit confusing as to painting, in one part it says common share expenses include painting, in another it says: 5.5 Landlord's Obligation. It is intended by the parties hereto that Landlord at its cost shall maintain in good condition the structural parts of the building, the roof, and exterior walls. Trying to figure out what to do!