Leak below roof vent due to failed poor mutin bar seal above or below.
Plastic conservatory roof leaking.
Thoroughly clean the area and fit specialist htg adhesive flashing to bridge the problem area.
The fowong butyl tape works to repair cracked roofs across multiple surfaces including metal fibreglass wood textile plastic aluminium and more.
Leak through the roof vent.
For what it counts and based on your initial message you may not need to replace the polycarbonate just the rubber seals and maybe underside spacer strips if any.
Repair tape maybe your best best if you ve seen that the cause of the leak is a physical hole to your plastic conservatory roof.