Regent Asset Management

My husdand has recieved a call and now a letter from Regent Assest Management offering a settlement of $430 from an old checking account he had with US Bank in 2003. I am planning on sending them a debt validation letter, but my question is what kind of debt is a checking account and what is the statue of limitations for this debt in Iowa. He thought that he had a zero balance when he closed his account and he called US Bank and they told him that he probably had overdrafts and they sold this debt to United Credit, he called there and was told that they sold it to Regent. At first we thought it was a scam because they are wanting $1522, they are saying on the phone that they are charging 18% a day, is this legal? Especially on a debt from 2003 that we didnt know about? This debt is not reporting on his credit report either, otherwise we would have questioned it. What a joke!:rolleyes: