Nadia Vole's complaints about Darrius Sayle are the four complaints that an unknown Stormbreaker character wrote in an effort to assist Mr. Grin to talk by allowing him to watch the movie Alex Rider: Operation Stormbreaker.
The unknown character who wrote these complaints sent them to Nadia Vole. Then, Nadia Vole gave them to Darrius Sayle, who fired her for writing the mischievous conplaints about him and his company, Sayle Enterprises. This allowed the unknown character to take Mr. Grin (Sayle's henchman who has no tongue) (when Mr. Sayle was busy yelling at Nadia Vole for all of the complaints she didn't write), bring him to her house, retrieved the movie Operation: Stormbreaker, put it in her DVD player, and watched it with Mr. Grin while giving him speech therapy.
.These written complaints about Darrius Sayle are Phase 2 of an unknown character's evil plot. (Phase 1 is Get the Alex Rider: Operation Stormbreaker Movie).