Seat Belt replacement help needed

Hi,

I was hoping for some assistance with an isue I'm having. I'm trying to replace the rear passenger and driver's side seat belts in my 2003 Octavia Ambiante.

However I've ran into a snag. I cannot remove the plastic cowling that he seat belt passes through before heading into the reel. From what I can make out, I can't see any points of interlocking and can only deduce that they have been glued into place.

I really don't want to have to break them off and I am looking for a quick resolution as the car has to go through it's MOT in under a weeks time.

Thanks in advance