We have a 2004 X5 diesel , fan won't turn off even after key removed, have taken out 50amp fuse to stop it ! would apreciate a solution please

In these models the temperature control works till the normal temperature comes to the engine. So if there is failure of the temperature control sensors- Thermistor- or if there is fault on the temperature controller unit , the fan will be made to work on till the controller deactivates.
So you need to check for the input- temperature sensor, check any wires that had come off the sensor or the unit, check if the fan control contactor/relay has failed or jammed on contact.( relay).
Try and trace these lines , check the action of the relay when the fuse is put on, if you hear the relay clicking then it works and the control circuit can be the suspect.