Leaking Double Glazed Bay Window

Would anyone be able to advise me? We have a bay window and water is getting in under the window. There is a void created by the plastic trim where the bay sides meet the front of the window on each side which seems to be where the water is coming in. (Pic of water on inside window sill).

Would you recommend filling these small areas and if so, what would be best to fill them?

Many thanks

 

Hi Riddor - didnt see the water coming in exactly. It appeared actually when someone jet washed the property as it was covered in mud, so may have been this that forced the water through. I have noticed the draft that blows through these gaps as well. thanks for your reply