St John is investigating why an ambulance didn't turn up for an elderly woman who was having a stroke - forcing her son to drive her to hospital.
Dave Hallie has written a formal complaint to the ambulance service about the failure with his 83-year-old mother on February 14.
He called an ambulance at midday, the same time as a woman who the Herald on Sunday reported two weeks ago was unable to get an ambulance for her son who was having a severe allergic reaction.
Hallie said his mother, Thea Hallie, had just been released from North Shore Hospital after having a heart attack on February 10.