What can i do about Midland Credit Mgt?

I have Midland (collections agency) listed five times on my credit reports (all three reporting comps) each listing different dates, different accounts, and all being reported as "disputed by consumer". They call my home on occasion claiming to be lawyers, etc....doesn't scare me. But I have sent validation letters--nothing, I have told the credit report companies and they do nothing but list it as disputed. Well, now I find another listing opened this year with Midland. How can they do this and how do I get them to stop. All my negative items were to have lapsed last year but Midland keeps them on there. In addition to Midland I still have the original Cap one cards listed with a first deliq date of July 2000 (should have been removed already. I have never had problems with closed accounts dropping when they were supposed to but this is ridiculous. What can i send them to finally validate or get off my report!