probably not a prolongation but just a fact that it was never officially announced how many episodes will the drama have so the 12 episodes stated here was just a guesstimate based on usual thai bl drama episode count. it happens sometimes :)
(i really hope there will be 17 eps, i love this drama, too!)
OMG ... I really hope it's true and that we will have more episodes. I really don't see how they can put everything that we have left in the book with one episode... and for the story of DeanParm only.