Just dispute the charges throught Trans Union. They must answer either way within 30 days or it has to come off. By chance do you still have the receipt that it was returned? If not,if you know the date it was returned, write a letter explaining the problem. Make sure it is sent 1 regular and 1 Certified and keep a copy.

Normally, you should never just pay a bill if you have valid reasons to think you don’t owe it. Do you have no proof you returned the modem. If you don’t then the simplest and quickest way would be to pay the item. Proof that you returned it would be something like a receipt or Proof of Mailing. Just your verbal “I returned it” will probably not hold up in any court.

First stop calling them. Any communication with them should be through certified mail with a return receipt. This way you have proof that they got your letters.

If you do have proof send a copy of this proof to the collection agency stating that it was returned and you want this item removed. They have 30 days to respond and if they do not respond in 30 days you can contact the Credit Reporting Agency(Experian) and state that they did not respond and have it removed.

If you have no proof, send a letter to them offering to pay the amount in full IF they remove the collection account. In most cases they will agree to this. However, do not send any money to them until you have a letter from them that they will agree to do that.

A well written letter is usually your best bet to get any situation solved. Then do a follow-up phone call. I find that you can never get anything solved over the phone with many companies. Or when you do call, ask to speak to a supervisor instead.