It's five years old and I use it twice a day every day. Tomorrow my partner will pull it out and have a look at the drainage pipe to see if there is a blockage. He drew the line at doing it tonight - he's been at work all week and wants to chill.
I think the heater has gone which is why it won't drain. I think there is a lot of congealed gunk in the drainage bit, even though it looks like new inside. How annoying.
I suspect it's buggered come to the end of it's life. White goods don't last like they used to. I remember my mother's twin tub when I was a child. When it finally gave up the ghost it was about twenty years old.