If you have a 3 plate ceiling rose with a switch drop then it's a case of checking why the switch drop is not switching the light off. Be very careful as you're not supposed to be testing live components. If you google 3 plate light you will find some explanations but basically you might find a lot of similar colour wires which can be carrying voltage and should have brown sleeves if they are a live or switch wire but might not.
A pic of the plate in the ceiling rose would help us to guide you.
If you have a 3 plate ceiling rose with a switch drop then it's a case of checking why the switch drop is not switching the light off. Be very careful as you're not supposed to be testing live components. If you google 3 plate light you will find some explanations but basically you might find a lot of similar colour wires which can be carrying voltage and should have brown sleeves if they are a live or switch wire but might not.
A pic of the plate in the ceiling rose would help us to guide you.