Droflet,
It can't be called science fiction because it's describing something that is happening in real life?
NO! There's nothing wrong with that still being a subject of science fiction.
That certain Star Trek episodes point to things like Naziism, colour prejudice or many other wrongs doesn't stop them being SF, it just means they are also relevant to today's problems.
But in the case of Never Let Me Go, I don't think they even were clones. They were simply kids who had been chosen by the society to be suppliers of replacement organs to the more powerful, and kept alive simply for that purpose.
Eventually they became proud of the service they provided in a sort of Stockholm syndrome.