Validation response incomplete. What now?

I am a Florida resident and I sent a letter to the collection agency requesting validation of the debt. They responded 42 days later with a letter stating:
- The name of the original creditor.
- Account number.
- Balance.
- My name and last 4 of SSN.
- A statement that they've purchased the debt, but no proof.

They didn't respond to the remainder of what I've come to learn are valid requests under FDCPA including my requests for:
- Complete payment history
- Copies of any agreement that allegedly bears my signature as debtor wherein it was agreed to pay the original creditor;
- Letter of sale or assignment from the original creditor to their company showing when it was purchased and who from.
- Prove the Statute of Limitations has not expired on this account
- Proof that they are licensed to collect in my state
- License numbers (and registered agent, if applicable).

I am thinking that I should write another letter stating that they've failed to fully validate the request, but how much time do they legally have to do so? And what exactly should I include, besides naming what was not provided?

If their time is up, can I request that the item be removed from my credit? If so, do I request that they do it? or go directly to the Credit Bureaus?

Any assistance would be appreciated! Thanks!