An 80 year old man whose life was saved by a defibrillator and a bystander passing by during a serious cardiac arrest at Cardiff Central Station has thanked the charity Welsh Hearts on their third birthday with a donation to purchase another device to get more of the life-saving machines  into public places in Wales. Frank Brock, who lives in Rumney in Cardiff, was picking up a friend at the busy railway station in February 2016 when he suffered a…