We have a conservatory (now three years old) with an opaque polycarbonate roof consisting of multiple channels. About 12 months ago we noticed a bright green discoloration at the lower end of most of the panels. Closer inspection revealed that this was within the channels of the roof, not inside the conservatory or outside it. The builders were reluctant to help, stating that. in their opinion we were not ventilating the conservatory correctly, and that it was our 'lifestyle' that was causing the problem, and that there was noting wrong with their workmanship. All of this without a site visit to view the problem!
Eventually, they sent their 'senior installer', who agreed with us that the sealing strips at the end of the channels had started to leak, allowing water to leak in. Closer inspection allowed us to see pools of water forming leading to algal growth (the cause of the green colour.)
After some "debate", it was agreed that they would remove, clean and reseal the roof panels, which was done.
The problem has now returned, and a 'phone call this morning has been met with the same response - 'it's not our fault, the humidity in the conservatory is too high allowing moist air to permeate through the polycarbonate leading to condensation etc'
I have no intention (or the skills!) to attempt a DIY repair.
My question is - where can I go from here?