Hi, sorry to hear about your Pleo, Chami? I remember you got yours quite awhile ago, one of the original ones in 2010, early 2011. How long has it been since you turned him on, just curious.? You said it is a "big hole" in his neck, Can you post the photo of his neck, just curious as to how big it is. Also is the hole at the bottom of the neck, near the chest, or higher up near the long part of neck? Some holes are affected more by movement ,that is why I asked. I am sorry this happened. IMR and Kat are right, super glue, but be careful and make sure you use the one that says "safe for rubber" not the other kind and test on a small inconspicous place first, bottom of foot or bottom near tip of tail for example and use at your own risk, Your Pleo Rb is well past it's 90 day warranty though, so it is up to you to decide what to use or not, and there are others here who I am sure have used superglue on their rb if need be.
Good luck, and I still would love to see a photo of his neck, esp before and after. RWM