Stock Price Moved during in-kind donation process

Hello,

In the year 2020, I donated stocks.  I initiated the process with my broker on 12/23 who shows that on 12/24 the process was completed from my broker side and the stock was transferred.  The stock was received by the recipient's broker on 12/28 and sold at $118.54.  That's what the charity put in the letter.  On 12/23, the stock moved between $130-$131.  On 12/24, the stock moved around between $128-$129.  for simplicity sake, let's just say, it opened at $128 and closed at $129.  I want to use the correct donation amount.  What stock price should I use to calculate the donation?  The Charity is not willing to change their letter since they are saying they "received" $X based on $118.54 stock price at which their broker sold the stocks immediately after receiving.  

Thanks,