A former paramedic has claimed a drug investigation has left Geelong’s ambulance service understaffed and overworked, and exhausted paramedics were more likely to make mistakes. The former paramedic, who asked to remain anonymous, said Geelong was relying on paramedics working overtime to cover a hole left in the workforce by the suspension of at least 10 members of its ranks. The source claimed Geelong’s ambulance service had been asking paramedics to take on overtime shifts every day since at least November. “Sometimes three or four text messages a day with three or four shifts in them,” the source said.