Get A Puncture and Pay for a New Tyre

My wife hired an Avis car in Cape Town and had a puncture on her way to returning the car. She was billed for a new tyre. According to Avis, for safety reasons, they always replace punctured tyres. I bet that most of us didn't know that, especially as there is no such policy stated on their contract. Do you replace a tyre after a standard puncture? No? I'm sure that the vast majority of motorists do not, so surely Avis has a duty to bring this unexpected policy to our attention in their contract? By the way, when I asked them to give me the 'damaged' tyre they failed to respond. You have been warned. Getting a puncture on our roads is hardly unusual.