Any recommendations for collection agency?

I have some people that initiated chargebacks and then admitted that they were wrong. Also, people have done chargebacks on packages that has their signature on it. But they still don't pay their bill.
Is there any company that I can sell these debts to and take them out of my hands?

 

Do u mean digital signature?

 

I mean, that they signed for the package when it was delivered. The name on the tracking number matches the buyer's name.