I'm having the same issues as well asyour PS3 not reading dual layer disc. But there are a couple of things you can try. You can get a disc cleaner and try that, or manually open it up and clean out yourself. You might need a new Blu-ray component though. Not reading dual layer disc is usually a sign of the laser dying.
Or you can do what I did. There's a video on YouTube where a guy put his PS3 standing up so that the disc entry is facing up and the fan/vents are facing downward to get his system to read the disc. I have tried it and it does work for some reason. Just make sure you give it ground clearance so it can vent the hot air. Posting from my phone so it's hard to post the video now, but you can search something like "PS3 not reading dual layer disc" and find it.
I finally tried (PS3 standing up), and sadly, it did not work. I guess I'll end up buying a new console whenever a sale shows up.