Those looking for more stories about oppressed robots on Doctor Who can check out the 2011 audio play Robophobia by Nicholas Briggs. A sequel to one of the best regarded Fourth Doctor television stories, Robots of Death, Robophobia doesn't cover a lot of new ground beyond putting the Seventh Doctor in the situation but it's an entertaining enough story.
As I noted in my review of "Smile" from the latest season of Doctor Who, there are problems inherent in treating even sentient robots as a metaphor for slavery race relations, problems which rendered the end of "Smile" ridiculous and embarrassing. Robots of Death handles the issue differently, taking time to explore the issue of an emerging sentience in a class of servant machines rather than throwing it in as a twist plot point. Robophobia is less interested in the robots, portraying them all as saintlike, endlessly helpful servants, but as the title suggests, the focus in the story is more on the nature of the the bigotry. Though, more than anything else, the story is a murder mystery.
Set on a transport ship, one of the officers, Liv Chenka (Nicola Walker), views footage of one of her crewmates apparently being murdered, along with the Seventh Doctor (Sylvester McCoy), by a robot. We subsequently learn that reports of the events of Robots of Death have been hushed up. When the Doctor turns up very much alive--and not having regenerated--some suspicion falls on him. Seven isn't terribly helpful, either, being in full master manipulator mode, he holds his cards close to his chest, something that proves fortuitous as characters realise there were conclusions about robots and people which Seven hoped they'd come to on their own.
The climax is of course a bit melodramatic but it's an interesting statement about how irrational human hatred can be built on buried or repressed feelings.
McCoy, as usual, gives a great performance and Nicola Walker is good as a one-off companion. She later joins the Eighth Doctor as a companion for a series of audio plays.