I live in Iowa and posted a message about a year ago regarding a collection agency. In August of 2003, I sent a certified letter to Stewart & Associates requesting validation of a credit card debt. I also requested that all attempts to contact me, be via mail. I had a phone call on my machine today, saying that I had to immediately contact them. She also said it had to be done before the 28th of May. What are my rights and what can I do?