Water Works Panel leaking water

We own a 2007 Sportscoach Legend that utilizes a Water Works Panel for water management. Recently we have started leaking fresh water from underneath the coach. We determined that it was coming from the fresh water holding tank. When we are connected to city water, not only do we have water from the city connection, but the it also fills up the fresh waster holding tank, so that when the tank is full the water runs out of the overflow pipe. We were told by a rv repairman that the hot water valve in the panel was bad. So we had that changed out. It still leaked. We were then told it was the fresh water valve, so we also changed that. We are still leaking. The handles are turn as per the diagram, to city water use. We have tried every combination of handles but we are still leaking. Does anyone have any other ideas as to what can be happening?