I am not sure why this would be such a dilema for you? I would always suspect the worst case scenario as a way of covering my behind. You were given an instruction by control for a way for gaining access to a person who may genuinley need your help/want it or not. This 'coded' access info must have come from the relative agreed? So if the patient refused to answer the door and deteriorated because you would not follow the instructions surly leaves you open to critisism? (Police would not be interested as you state) advice from control would probably not help either, leaving you with no option but sit there for hours waiting for relative/further instructions etc. Now if you did follow the instructions, gained access (even an open door) - saw that the patient was not suffering life threatening inj/illness and deemed capable of making thier own decision not to travel - then you could leave and your concious would be clear that not only have you followed instructions (No sacking today) and you havent left a patient in genuine need? To me that is a win/win situation? By following that specific instruction - I don't think is beaking the trust with the patient as you do not enter the property unless invited?