Engine refit

I recently had the camshaft collapse on my 2006 S type 2.7 diesel V6. I have had the engine reconditioned however they are claiming some of the bits are missing on refitting the engine. Mainly the wire coming from the coolant sensor and the sensor itself. This seems to have resulted in the dash warning low coolant level/restricted performance, which it has. Is there a wire or sensor that fits under the coolant bottle or are we looking for something that does not exist. It is being suggested that a complete wiring loom may be needed???