Billing errors and documentation

I recently moved. When I moved, I shut off all services at the old house, and opened them at the new one. I had my mail forwarded, and I gave my new address to all of the people who needed it. All of my final bills came to me and were paid. Except one.

Bell South sent my bill to the new street address, but the old city, like so:

123 New House Street
Old Town, Florida

So as a result, I never got the bill. Three months later, I am contacted by a collection agency. I call Bell South and ask them why I was sent to collections, and the problem is quickly identified. I point out that since the error was theirs and not mine, that I will pay what I owe, but that I will not pay late fees, nor will I pay this unless I get a letter that states that the collection will not be placed on my credit.

The lady tells me that they don't do that, and that I should just pay. She goes on to say that since the letter was not returned, the fact that I did not get the letter is not their problem.

The problem is that I will not pay a late fee that was not my fault, and if I pay at all without such a letter, nothing prevents them from placing a black mark upon my credit record.

I send a dispute letter to the collector AND to Bell South. Bell South sends me a copy of my last three bills, and these copies clearly show that they had the address wrong.

Funny thing is that the collection agency manages to get the address right. Since my dispute, they have both ignored my letters, and continue to call. They call me, they call my girlfriend. They send letters. Soon, I am sure they will place this on my credit record. When they do, they are going to force me into suing them for violating the law.

Why can't businesses just do business in an ethical manner? I want to pay this, but I also am not going to ruin my credit for the next seven years because of an error on their part.