I have received letters from this organization (letterhead says "Yachad - National Jewish Council for Disabilities - an agency of the Orthodox Union" thanking me for my pledge. I did not make a pledge. When I spoke with the organization in the past, they told me they would correct the error and remove me from their solicitation list.
The problem happened again, and the organization told me that it must be "something due to our outside contractor that does fundraising".
Sending a letter demanding a "pledge" that was never made is fraud.