Responsible for unauthorized property tax payment?

by Jennifer
(San Jose, CA, USA)

I received a letter from BAC Tax Services stating that they mistakenly paid my property taxes ($3040.26) back when I still owned my Oceanside, California home.

BAC/Bank of America was not my mortgage company. They just typed in the wrong parcel number when making a payment.

Since then, I've short sold my home, so I was not even paying my property taxes at the time. The letter said that they confirmed that no duplicate payment is currently posted on the parcel, and now they are threatening to send my account to a collection agency. I am worried that this will show up on my credit report, but I do not have the money to pay for it and feel that it was their mistake and I didn't authorize it, so why should I have to pay it? If they didn't pay for it, it would have been apart of my short sale...

Can they do this, and will it affect my credit?