A user who does not wish to be identified writes:
I had one article rejected with only one reviewer and the editor did not want to contact a second reviewer.
I know who was the reviewer and also why he rejected my paper, since he became now the new supervisor of my old PhD student.
What should one do in these cases, please?
From my personal experience I think it is very unfair the reviewer has the license to insult persons on the bases on his “official” animosity.

Maxine responds: we cannot provide advice about specific papers or journals that aren’t Nature journals, but in general, if an author is dissatisfied with the peer-review process, he or she can write to the journal to explain the (scientific) reasons why. The journal should have a complaints procedure described on its website which you can follow. If not, write to the editor in chief or to the editorial board, which will be named in the journal.