Need address to send Paypal credit/Synchrony Bank a demand letter

I have had a problem with paypal credit since March 2021 where they opened a dispute on my behalf, against my clearly stated wishes, when I called to inquire about the interest rate on an audio purchase I had just made.  They took the seller's money and I felt responsible (although I know it was in no way my fault) so I had him send me a money request for the funds paypal took back.  The request clearly indicated it was a REPAYMENT and listed the item, the tracking number and date delivered, obviously not a new purchase.  I work nights so it took a couple of days to get ahold of paypal credit to clear up the situation.  I told them I did not open a dispute and that I'd sent the seller another payment to replace the one they'd taken from him.  I requested they void/nullify their dispute but the csr said they couldn't do that and the matter would be forwarded to the disputes dept.  

Voiding out their invalid dispute would have resolved the situation OR they could have dropped the dispute that I did not initiate and simply return the seller his money and had me cancel the REPAYMENT.  No, they did neither.  And a month later I was told I lost the dispute and the purchase amount was put back on my bill.  I called and challenged this and around and around we've gone for the last 17 months.  Despite several calls and emails,telling them not to, paypal credit sent the seller the dispute payment a month afterwards.  And once the seller received the extra payment, he ceased to respond to my emails.  

So, I've had numerous calls, emails, and even wrote an 11 page letter with full documentation showing all this and the emails between the seller and I to no avail.  I have had 2 managers, after a complete walk though of this, tell me I owe them nothing and the fault was all theirs.  They told me they'd take care of it and then, well, I'd receive another message saying I lost the dispute and billing would begin again with late fees +++.

I am, therefore, forced to make this a legal matter as my credit has dropped well over 100 points due to paypal credits erroneous reporting.  I'll try small claims on my own unless some consumer protection minded lawyer would like to take this on as a contingency fee agreement.  Any advice would be appreciated.  Thanks to all.