Aargon Agency, Inc Picking up a bad debt that's being closed a long time ago and posting it to my credit history Saint Louis Missouri

I don't know why they post debt on my credit history and mess it up For the record, I do not owe Laclede gas or any entity in Missouri any amount of money. I
moved out of Missouri two years ago, paid all my bills and cancel all account I have with any organisation. The only debt I have tied to Missouri is my student loan
which I am already settling. I don't know why this company will post a debt $150 to my credit history and mess it up all up. Another collection agency  did the same last May and I called Laclede gas and that organisation to have this corrected. I think this will keep repeating itself until it is sort out. I mean you can not just go
pick up a bad debt and post it on people's credit history because you have access to it. That's absurd, it is like messing with people's life. This is really unprofessional especially when I do not owe any amount. Please, ask Aargon agency to have this corrected and never to mess with my credit history again. I might file law suits if this ever repeat itself.