I hired a plumber to convert separated hot water and cold water taps to a single mixer tap. He cut a hole in the wall and removed a section of timber (as shown in the photo). He left without fixing the wall. So I have to finish the job. I've already got some villaboard. However I don't know what is the best way to re-attach the timber that he removed. It's used for the support of villaboard. Any suggestion would be appreciated.
