A while back I got a letter from a debt collection agency seeking to collect from me. I immediately knew the debt was not mine, so I sent the collection agency a "put up or shut up" letter disputing the validity of the debt. They never replied so after 30 days I figured that was it.

Now about 5 months later I have been contacted by a second collection agency about the same debt, apparently they were hired by the original company that thinks I owe them something. Do I have to repeat the dispute process, or can I just point to the original dispute and tell them to get lost? Can the original company just keep hiring different collection agencies every time I dispute?

Thanks for any advice!