Bathroom extractor fans will typically have two connection points - one inside the unit itself - the one best for disconnection.
And another in the ceiling rose - where the lamp hangs down.
There are usually three wires - live and neutral to drive the fan and switched live from the light to trigger operation when the light is turned on - turning the light off will not stop the fan - it runs on a timer.
Do not be tempted to disconnect the wires at the lamp - just mess with the wires in the extractor enclosure.
Alternatively call in an electrician - it's safer
Good Luck...
February 2016
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix electric fans.