A collection agency told me it couldn't remove a paid debt from my credit report because it was illegal under the Fair Credit Reporting Act. Is that true?
They can do it, but they'll always tell you they can't. Be persistent, and if you truly want it deleted, don't be too greedy when negotiating a settlement amount.
You need to do your own research on that matter. Reading and understanding the law isn't hard. If there is anything stating what they told you in FCRA I have yet to find it. If you can't find it in FCRA then I'd file a federal case against them for providing false and misleading information to a consumer. Of course, you would have to be able to prove that they said it either with a written statement from them or a recording of them telling you that over the phone.