A couple months ago we had a customer who normally sent wires out of his business account send one out of his personal account and we did not give the required remittance disclosures. Any thoughts on how to cure this?

Do you have anything recording the purpose of the wire (personal, family or household purposes? Yes or No.) or anything showing that it was not a foreign transfer?

We do not have the purpose, we just know it came from his personal account. It was a foreign transfer.

There's nothing in the regulation about a cure. You can cobble together a disclosure/receipt and send it to the Sender. That, at least, will disclose his error claims rights in case the wire didn't arrive on time, etc.

Figure out what changes in procedure you need to make to prevent this from happening again, if you haven't already done so. You can assume that all foreign wires from consumer accounts are subject to Subpart B Regulation E requirements, and that those from business accounts or other non-consumer accounts are not. Or you can make sure you get a purpose statement on every foreign wire (consumer, family or household purpose: YES or NO?).