Misleading information from CA

Dell doesnt usually sell their debt, at least not initially. The person you spoke with at Dell probably doesnt understand collections.

When you are assigned to a CA, you no longer have the right to deal with the original creditor. Collection agencies are hired under contract, and part of this agreement is that the original creditor no interfere with the CA's collection efforts. The original creditor is contractually bound to pay commision on all payments received during the length of the contract thus they are not going to waste their manpower hours doing what they are paying someone else to do.

I disagree. You do have the right to contact and attempt to deal with the party with whom you contracted and owns the debt. They, however, have the right not to deal with you if they have hired a debt collector as their representative in that matter.
Right or wrong in their reason for refusal to deal with you, which was in this case their assertion that they legally cannot do so because they no longer own the debt, they can require you to deal with their representative without the need to substantiate their reason.

I dont know what type of deal you planned to offer the OC, but whatever it was, just send it to them in writing. Let them tell you that they no longer own the debt. Until advised otherwise, you have the right to deal with them, but not the right to compel that they deal with you.