Disputing debt collections.
Hello,
So the beginning of March I received a letter from a collections agency saying I owed an energy company $450. However this is ridiculous as I had not had an account with them for three years and had proof I closed it out and paid all that was owed. However I six at checking my mail and it said I had till that day (the day I saw the letter) to dispute it. I got the letter after they closed so first thing in the morning I called them to dispute it which they allowed me to do. They also said the energy company had till May 11th (today) to respond.
I have not heard from them since. Not seen anything on my credit report, no letters, nothing. How should I proceed? Should I assume the debt has been dropped? Should I call and ask? Every thing I have seen regarding communicating with collections is to do it via mail but am not sure.