There are companies that will come to your home and make such a repair for as little as $50. It sounds like a lot, but consider the cost of replacement as a comparison. You can make a patch on your own with Bondo (or some other fiberglass patching compound), but chances are the homemade repair will be pretty obvious and may become eyesore. Isn't $50 bucks worth an invisible repair? Look in the yellow pages under plumbing fixtures, repairs.