Did they actuallyl verify this debt?

Last year I pulled my credit report and found that a company called afni had reported a bad debt with a cable company for $39. I double checked my records and I have paid that cable company under a different collection agency in the amount of $129 (final amount of the bill) some time ago. I have not had service with that company since and they were bought out by another company some time ago. I contacted AFNI who of course didn't want to hear anything other then how I was going to pay them and the company that bought out the cable company wouldn't talk to me. I sent AFNI a letter and a copy of the canceled check and their response was that the account number I had paid under didn't match their account number. Well neither numbers from the collection agency matched the original account number from when I actually had service. So I sent a letter asking for validation of the debt and all they sent me was a letter stating it was validated - no statements or info on where/when/how etc. I challenged this entry when it was still on my credit report this year and the only response I got was that it had been validated with the company reporting the debt.

I realize that this is a petty amount to be dealing with but I had crappy credit for a long time and FINALLY have paid everything off and as of last month my FICO was finally up to 676. I really would like this cleared up. What can I do? Is the debt truly verified if all they have sent me is a letter saying that it is verified? Don't they need something more concrete than that?