Goodwill follow up advice

First the backstory. Recently I missed a payment on a mortgage with Wells Fargo. We have two mortgages with them and while I believed I had paid both I missed one. This was in the midst of an Ice storm which knocked out power for us for a week, and others for longer. When they notified me of a late payment last week I thought it was in reference to February's payments. Then Saturday I got a notification for my credit report and quickly discovered my error. I immediately paid the missed January payment. The following Tuesday (Monday was a banking holiday). I called about the issue predictably without success. I then found examples of goodwill letters and this helpful archived post https://old.reddit.com/r/CRedit/comments/1g4jzcj/goodwill_saturation_technique_gst/

I faxed a letter in on Tuesday and actually got an overnight response yesterday also declining to help and citing their responsibility to report accurately. They included a specific extension to call with any questions and also requested if I have additional information to send that in as well. My questions are:

1. Do I call or just stick to the fax and then other mailing addresses with my letter?
2. Does sending additional information help. Our area did not get a full FEMA support so Wells Fargo does not see that. However, we did get Public Assistance for emergency infrastructure repairs which I can document.

Let me know if there are additional details I skipped over that may be helpful providing any insights. This is my first and hopefully only go at something like this. Having this hit to our credit report for 7 years would definitely be problematic.