All excellent answers, and there is also a 'plan Z'. Email them the photo, stating that you own and possess the copyright in the image, which would be enforced. If they choose to use the photo, you are then in a position of power to demand a higher retrospective licence, or sue and receive damages.
I know that this may sound like an unusual plan, especially if you don't want a court case, but this is standard practice among emerging artists who are glad of the exposure that plagiarism beings them. I could name more than a few cases!