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Indeed. They do not have any contact details, except for my email and an IP address, which they can presumably use to track back to an ISP.
So far our dispute has been conducted via email, and indeed it may be a scam, so they need to write to me directly. As they don't have my contact details they are threatening to submit a court order to force the ISP to divulge my personal information. Of course, they also have my credit card details but have not threatened to approach my credit card company presumably because that would not work.
I've also contacted my ISP for their position, but they have yet to respond.
My understanding is that as this is a civil, not criminal matter, and does not involve copyright infringement then they are not legally obliged to provide my details. Further, under the DPA they are legally obliged to protect my information.