I think it's best to just send a copy of the letter I sent to them minus personal info. Here it is:
Hello,

Why are you continuing to contact me over this dispute?

I submitted a dispute form, spoke with your representatives twice at length and called ****** Care accounting department. I was finally able to gain information on why this claim wasn't paid, after speaking to an accounting agent from *******Care. I was unable to get any of this information from your representatives both times that I called.
I was even told that this information (the reason claim wasn't paid by you) wasn't something your company (Oneshare) provides.

*The reason that your company didn't pay this claim was because of your policy time limit on when the claim was filed.*

*******Care initially filed the claim Aug 2020 and it didn't go through for some reason.
*They don't know why it didn't go through.

*******Care refiled the claim with you (Oneshare) again on Oct 2021

You, (Oneshare) responded to ********Care on Oct 31st stating it was an untimely payment filing and that you do not pay claims after a certain date.

*It was suggested by the accounting agent I spoke with, that you call *******Care accounting department directly. This is the info you'll need to contact them:

I requested a three way call with your agent the second time I called Oneshare to resolve this mix up and she stated she was unable to conduct a three way call. I then asked if she could call them directly. She stated that she could not call their accounting department. That is confusing. The accounting agent I spoke with at ******Care stated that they conduct three way calls frequently with companies they file claims with. She kindly unraveled why this claim wasn't paid by your company, after I had attempted unsuccessfully to get this information from you.

A few other key points:
******Care is no longer asking you to pay this claim. I was told by their accounting department that they're incurring all fees associated with this claim.
It is confusing why your company claims that my policy didn't cover the fees and that is why you continue to pursue this claim that you don't have to pay. This is untrue and misleading.
The language and wording you use in your communications with me, made it appear that you (Oneshare) had paid the claim and I was now responsible to pay you the claim amount.
I find this extremely unethical. If I were disabled, elderly or just couldn't unravel all of this confusing communication, I would have probably given up and written you a check for the claim amount, when it was never paid by you (Oneshare).
I am a true Christian and I find it reprehensible that your company tried to extort payments that are not due to you based on your confusing communication and being non transparent about why the claim wasn't paid by your company. I asked repeatedly about why the claim wasn't paid and was told my policy didn't cover it repeatedly. That was completely untrue and added so much time, confusion and stress to unraveling this mess. This seems intentional and I'm sure it adds to your profit.

This is a formal request for you to stop contacting me, or if you prefer we can go to court. Your company is extremely unprofessional and in my opinion, very unethical.

Please share this communication with your CEO. I think he should evaluate your company's communication and the way you treat customers.

Cordially,

***********