Thank you for reaching out to the Community with this. I do see you were able to contact a couple of our support agents so I'm hoping they were able to assist you, but just in case I do have the answer for you.
What you're seeing is actually the picture associated with a post created through our Social Share feature, not the Facebook Ad. Facebook Ads never pull from any of the stock images we offer for Social Share posts. They only pull from pictures from within the campaign being used as the advertisement. The post you are seeing is only visible on your Facebook business page and only to people who "Like" or visit your business page. You could always delete the post from your business page and then create a new Social Share post to take its place. This will not impact your Facebook Ad whatsoever.
Click here for a helpful step-by-step tutorial on how to create a post in Social Share.