the material was inferior or you used brillo pads or acetone for cleaning. We replaced the lewmar port plastic on Tappan Zee about 2 years ago and after mostly ignoring them and occasional fresh water with simple green and even rarer cleaning with Plexas they are still perfect. We have been in blowing dirt and salt S. Calif. and Mexico so my view is your vender's material is defective and they are blaming you. Is there an owners group? Others may be having the same problem. Good luck. Tom Evans San Diego