Can a vendor change the status of a house after exchanging contract? what is the legal implication of this?

we have recently exchanged contract for a purchase of a house. However, we found that the vendor has taken some valuable items from the house before completion. we noticed this when inspecting the house for the last time to complete the process. He removed something from the boiler so the boiler is no more functional. He closed the gas and switched off the electric so no gas or electric in the house. the house had a beautiful fire place but has been removed after exchange. some decors on the ceiling and lumps have been removed. when viewing the property all these items were in the house. Do I have to complete in this cirstances? Can we refuse to complete if the vendor refuses to return what has been taken from the house?