They were after me for over a year for money I didn't owe. Here's how I stopped them cold with one letter:
Send a letter to whomever sent you the bill (a collection agency or Columbia House itself) by CERTIFIED MAIL - RETURN RECEIPT REQUIRED (this is your proof they received the letter). This will cost you about $5, but it is worth it. When you get the green slip back, staple it to the letter and store both safely for at least three years.
In the letter tell them:
The account number listed
The balance they indicate you owe
"I do not believe I owe this debt"
Enter this paragraph, word for word, except for changing the info in brackets [ ] to fit your particular state:
Section 805 of the Fair Debt Collection Practices Act requires that you provide me with ALL of the following information:
The name and address of the original creditor
The date of the original transaction
The amount of the original transaction
The date you acquired this debt
The amount you now claim is owed
The names, addresses, telephone numbers and social security numbers of all parties associated with this debt
Proof that I owe this debt
A copy of my State and Federal rights concerning this debt, including information on how to dispute it
Proof that you are licensed in the State of [your state], as well as providing me with your [your state here] license number.
You are aware, of course, that you cannot contact me further until this information is provided in full.
[end of letter]
after your signature add:
cc: [name of your state Attorney General]
State of [your state]