Dispute not responded to on collection. Get it off my credit report

I have come across your Website and I would like to ask you a question about Collection. I had cleaned up a collection I had on my credit report. I disputed with the credit reporting agencies, (Experian, Equifax and TransUnion). After the 30-45 day waiting period the collection and or Creditor did not respond to the dispute, therefore it was removed from my credit reports. All that happened in October 2006.
Cavalry (http://www.cavalryportfolioservices.com/) stating that they purchased that Account from Sprint PCS, which is the one that was removed 6 months prior by not responding to the dispute.

Is it legal that they can do that? Can you please advise me on how to proceed? Is that common that they just keep sending and or selling that account around for years to come?

I greatly appreciate you help and service.
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Subject: Re: Removed Prior Collection

http://www.oskie.com/how-i-get-paid-collection-collections-account-removed-credit-report-completely.htm

Have em validate the debt.
Most times this makes the rats hide in the basement.
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Thank you for the info you have given me on validation. I have sent them the validation request letter certified. I have not received any info from them so far and it’s been 40 days now. Do I need to contact them again to asked them to remove that item form my reports?

I really appreciate your help on that matter.
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You need to follow up for sure.
I would call and verify they are working on it.