He came to replace the worktops (as the original ones' seals blew the minute water got near). Whilst removing the old surface, he's knocked a large (4"x4") chunk out of the plaster back to the brick. He has shrugged and said he was trying to save the tiles from cracking. I said that was commendable but irrelevant as I didn't want either damaged. Now he's stomped off, saying I'll have to talk to the office about it. AIBU?