AndoniP,
Re
“I assume that the CVR was analysed in this instance and action taken? A question from SLF - are CVRs checked after each flight? Or only when there's a complaint or problem from the crew?”
CVRs are very rarely checked, maybe once or twice a year in a typical airline and then usually at the AAIBs request who will not divulge its contents to anybody. In general CVRs are there for post accident analysis and should never be used for disciplinary events.