We have new neighbours who have moved into an attached property. They are building an extension that we had no objections to in the planning stage and had no issue with them using our land for scaffolding. However I got a uspet phone call from the wife yesterday who was rather upset saying they were building over our property. She is mostly upset because we are currently in the process of sorting our own work and their extension appears it will encroach on our plans. The fence in the photo we built on our side of the property line and is only about 6 inches from there new brick work. I have spoken to the builders explaining they can't build over my property there, but I got the feeling they were just ignoring me. So my question is what should be our next course of action?