Identity Theft

This morning I got a letter in the post from Virgin mobile. It said "Thank you for arranging to pay your mobile bills by direct debit; please contact us if any of these details are wrong".
I didn't recall arranging to pay for a Virgin mobile phone by direct debit, so I phoned the number. After about 30 minutes of listening to annoying music as the Virgin organization tried to figure out what to do with my phone-call - it wasn't appropriate to talk to the direct debit department about it, of course; no, I needed customer service... - I eventually spoke to a nice lady whom I'll call Mary. Mary asked me a bunch of questions about the letter and me (including, strangely, asking for my Virgin mobile password, which didn't seem relevant), and then she explained (after another few minutes of elevator music) that it seems someone else is using my identity (name, address, date of birth) to register a phone. It's not clear to me why they would do this, as the direct debit wasn't coming out of my bank account. Anyway, she said she would file a Fraud Alert with the Credit Report people, so maybe my name will be blacklisted from credit requests in the future.
She recommended that I contact Equifax to find out if other credit application frauds have happened using my name, and whether my credit score has been damaged. So I took at look at the Equifax webpage, and found a bunch of Equifax organizations, all with the same logo, all rather keen to take my name, address, date of birth, credit card number, and other security details. And keen to charge me money to answer the question "what is my credit history, and is anything funny going on?" I'd never heard of Equifax before and once bitten.... I feel rather reluctant to go typing all my personal details into a form. It seems Equifax are an international organization that handles everyone's credit history. And then charge everyone in sight for that information, including banks and the innocent civilian.