It is repairable, but like Festus said, I'd leave it to someone with experience in dealing with fiberglass and such.
Our Vantage developed stress cracks on one side of the rear fiberglass cap, right where the screws hold it on, on it's first outing. Took to local dealer and they fixed it under warranty. Not sure what exactly was done, but the guy in service dept said they'd have to take it to a fiberglass guy they routinely deal with in order to get it done properly.
I realize you're saying they're in the filon rather than fiberglass, but since filon is a form of fiberglass sheeting...
Edit to add - stumbled across a site where person details building a teardrop trailer using filon
http://www.outbackteardrop.com/ (which in itself is an interesting read) and in it (on page
http://www.outbackteardrop.com/body4.html ) he says that all filon is made by Kemlite Corp. and that their factory techs are quite helpful. So, might be worth getting ahold of Kemlite if you think you might be up to the challenge of repairing yourself, or even just for finding out proper way so that you know that person repairing it is doing it right.