Product: Payday loan, title loan, or personal loan

This is a copy of the letter sent to Comenity : I was advised to write directly to you by several of your telephone representatives today regarding the aforementioned account. 
I will first proceed with a summary of the events together with my comments ( italicized ) : On XX/XX/2019 I attended a seminar sponsored by the XXXX XXXX XXXX  company primarily for the very expensive XXXX model. 
( seminars are frequent in this part of Florida and, I suspect in many places in Florida and throughout the United States. Together with financial seminars, they typically target retirees and senior citizens and use unscrupulous techniques to sell their goods and services ) .The speaker was XXXX XXXX XXXX of XXXX/ XXXX XXXX XXXX XXXX of XXXX, Florida. 
During the seminar, the XXXX representative and XXXX XXXX offered a free XXXX XXXX and trial of the XXXX XXXX XXXX XXXX XXXX. 
Wanting to have the evaluation, I set up an appointment for XX/XX/2019 at XXXX. At that appointment, I had a XXXX XXXX and ( as expected ) exhibited am age related XXXX XXXX. XXXX XXXX felt I would benefit from a set of XXXX XXXX. She set up an appointment ( XX/XX/2019 ) for a fitting which meant having a XXXX XXXX made of my XXXX XXXX, since the recommended XXXX XXXX XXXX   could not be used without them. I was advised to try them for 30 days and if no improvement was noted, or there was any problem, to return and the units would be exchanged, or a full refund would be offered. 
At the time of my first visit, I filled out and signed a number of documents allowing for treatment. Among these was a form for XXXX, affiliated with Commenity Capital Bank. This was apparently for again free-financing of the very expensive XXXX XXXX. ( over {$5000.00} ) Within a week, I returned the XXXX XXXX, noting no difference in my XXXX  and received a refund-less a {$650.00} restocking fee. 
I complained about this both to XXXX XXXX office and XXXX XXXX. Afterwards, I did receive a {$350.00} refund, as well as {$4900.00} credit for the returned XXXX XXXX. 
At the end of XXXX, I left the United States for 5 months to the XXXX XXXX and XXXX. During this time I had constant Internet access. 
Apparently the balance on my free account and services remained at nearly {$600.00} and was charged interest for the entire time I was away. I was apparently sent invoices by US Postal Service, but never received any e-mail correspondence from neither XXXX, nor its associated Comenity Bank. Handling over 160 credit cards with over 50 million cardholders, Comenity certainly had the ability to reach out to a delinquent account and ask for payment. This was never done. 
As a result, the account was never dealt with and upon return, I received a dunning letter from XXXX XXXX XXXX advising me of the situation. 
All of these activities resulted in my credit score lowering by over 100 points and the amount owed remains. 
After speaking with the XXXX XXXX, I was advised to contact Comenity Bank and explain the situation, which I did. After being shuffled round I was finally told that theres nothing we can do, since the account was written off and sold. I subsequently learned that in such situations, the account could be bought back-but this was rarely done, even if the Bank is at fault. 
I am hoping someone reads this letter that can produce reparations, rectification to my credit and a response from Comenity and stop such predatory practices and scams on often vulnerable Seniors.