@ubernostrum it's going to cost you $300-600 for that letterhead. Your options are that, pay the amount they're pestering you about, or ignore them. Or, perhaps a secret fourth option, you could try calling their legal department and let them know that you will pursue legal action unless they desist. Make sure you have a one sentence ("I received a collections notice for an account that doesn't belong to me"), 30s, and 2m summary of your issue so you can escalate appropriately