You're going down the wrong path.
If you've already written too many letters, stop the damage before you make it even worse.
Your letter will not do them harm in court. You borrowed money from them under the terms of a contract. You defaulted. They are under no legal or contractual obligation to settle with you for less than 100%.
If I were in PA and wanted to record the call, I would wait until they told me the call was recorded. I would say: Ok, the call is recorded.
UCC simple contract? You owe them money. If this gets to court, you will get nowhere with UCC simple contract. The judge will look at their evidence and award them everything, including attorney fees and other costs.
If you want to settle, it's possible for about 10-25% of the balance, and depending on the OC.
If you post the names of the OCs, I and others can give you a rough idea of who will settle for what %.
Again, there's no reason to pay a JDB a dime. If you wait, they will likely violate the FDCPA and PA law, allowing you to collect money from them. If they sue you, attack their evidence as hearsay.