Our advice would be to get a conservatory roof specialist to visit and check out the scope of the repair work.
Plastic conservatory roof leaking.
Thoroughly clean the area and fit specialist htg adhesive flashing to bridge the problem area.
Slipped or cracked conservatory panels can be repositioned resealed or replaced entirely to eliminate leaks and restore the watertight seals of a once leaking conservatory roof.
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.
The fowong butyl tape works to repair cracked roofs across multiple surfaces including metal fibreglass wood textile plastic aluminium and more.
A conservatory roof leaking in centre could be due to a slipped or incorrectly fitted roof panel a cracked glazing unit or a perished seal.