<human>: My coworker recently received a letter of debt collection for over 3K on a credit card they never opened.

They payed off all their debt in 1994 and this card was opened in 2002, even though they have always paid cash for everything since becoming debt-free.
The letter was received within the last 48 hours and the collections company was contacted about the situation. To which they said to open a dispute for the situation to be checked out.

Do keep in mind the least expensive manner would be best as they recently lost most of their life savings due to unforeseen medical expenses.

What's the best course of action to move forward?
Thanks. :)

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Coworker sent letter of bill collection. Hasn't had a credit card in 21 years. Card was opened 11 years ago. What to do next?