A: You have every right to be unhappy about this, they are your cakes and your photographs.
There's a common misconception that because there are so many photographs on the internet they must be freely available for everyone to use! This is generally NOT the case as Copyright to photographs for example is an automatic right under the Copyright, Designs and Patents Act 1988. This basically means, if someone else is using your photographs on their website, blog or social media sites they are breaking the law!
I have found, yes it's happened to me too, that if you contact the person in question and enlighten them about copyright they are usually only too willing to remove the photos immediately, most people don't realise they are breaking the law! If this doesn't work, you can report a violation of the Facebook Terms to Facebook itself, instructions and help are on their site.
Note: if someone simply shares a photo on sites like Facebook, Pinterest, Tumblr that's slightly different. I love it when my cake photos are shared on Facebook and Pinterest as it means many more people can be inspired by my work.
Moving forwards, consider adding a watermark to your images, opinion is divided on this but I have found that people think twice about using an image that is obviously someone else's.
I hope the above suggestions help. Happy baking