I already paid

Have you sent Palisades a debt validation letter yet? If not, I would send them one via certified mail/return receipt requested so you will have proof that the letter was received. Here is a template letter that you can personalize and use.

http://www.debtconsolidationcare.com/letters/sample6.html

Also, I would state in the letter that you are requesting Palisades to cease and desist all telephone communications to you at your home and or place of employment, and that all future communications should be sent to you in writing via USPS mail. If Palisades continues hounding you by phone, they'll be in violation of fdcpa regulations and you can get them on this.

You have provided proof of the debt being paid, so if Palisades have placed anything derogatory on your credit reports, dispute them with the credit reporting agencies and provide the proof that the account has already been paid. The credit reporting agencies should remove any negative entries that Palisades have made.