My son hired a mid-sized Ford Transit from a hire firm for a two week cycling trip. During the loan he got a puncture and the hire firm came out to replace the tyre. He now finds on his credit card that they have charged him £220 for the tyre. In fact they charged him twice which made him spot it. He has contacted the firm who apologise for double charge, but the small print seems to say we are liable for original charge. Does this sound fair?