Honestly, I would read chrome fork as also meaning non-original fork. I also think it's unfair to assume the seller knows everything about the bike or fork in question. I'm going to disagree and say they did nothing wrong and that the wording would have acted as a red flag to me. I'm also going to say whether they owe you a refund depends on the selling price and value. If I were the seller, I'd offer to give a refund on the whole bike...but I probably would not offer much of a rebate. Maybe a small amount (depending on selling price) just for ease of transaction.