Am I liable for a refund issued by mistake?

[QUOTE=Dag Otto]
You’ll want to check out sections 805 and 806 of the Fair Debt Collections Practices Act. I’ve read in other threads that the magic words are ‘cease and desist’.
[/QUOTE]

Fair Debt Collection Practices Act **does not ** apply to creditors collecting their own debts. You might have similar rights under state law, though.

Every U.S. jurisdiction in which I have researched the issue recognizes a cause of action for money paid by mistake. Check out Form 7 in the Federal Rules of Civil Procedure for example http://www4.law.cornell.edu/rules/frcp/Forms.pdf

This search reveals many copies of the same form in various state rules: Google Search

[QUOTE=Gfactor]
Fair Debt Collection Practices Act does not apply to creditors collecting their own debts. You might have similar rights under state law, though.
[/QUOTE]

Sorry, I misunderstood, I guess. They sent it to an outside collection agency then?

Incidentally, the Fair Credit and Billing Act, which is easy to Google, covers original creditors and their debt collection practices.
Also reference the Fair Credit Reporting Act if you like.