Never settle a debt with a creditor without getting it in writing from them. Here is a letter you can send them to sign. Be sure to insert your terms

You may or may not receive confirmation of your agreement in the mail or via email.  Suppose you have worked out a settlement with a credit card company or collection

Under the FDCPA, you are allowed to challenge the validity of a debt that a collection agency states you owe to them. This validation letter incorporates a debt settlement offer