A Dog's Life (short story)

Plot
When K-9 starts to start and stop working at random times, Sarah Jane is really upset. K-9 finds himself stopping people who want to steal some of Sarah Jane's things. Sarah Jane knows hat K-9 stopped them but lies and says that she did.

At the end of the story it is the bit from School Reunion where the Doctor gets K-9 to work.

Book
This story was in the Doctor Who files book "K-9".

K-9s
K-9 mark I

K-9 mark II

K-9 mark III

K-9 mark IV

Other K-9 mark III stories
A girl's best friend

School Reunion