Photos used by sites without permission

Recently I was lucky to be in the right place and the right time to get some dramatic photos that drew some interest from press.
I gave permission to a local paper to use the photos, for free with a name credit, on their facebook page and to print two of them for a nominal payment.

I now find photos from the facebook page, published on broadsheet.ie (with name credit) and also on a company website (not for profit, just as a news article) credited to RTE with no attribution on the photos. Neither one asked me for permission. I should add that anyone who asked the local paper for the pictures they referred them on to me.

Can I just invoice both organisations for the use of the photos, and are they obliged to pay or have I effectively given my rights away already? No point in asking them to remove them now.