A scrum over millions of dollars a year in ambulance-service profits in San Diego has taken a hardball turn, as long-time provider American Medical Response retained a law firm to formally protest the city’s decision to go with a rival company.

According to an eight-page letter from Los Angeles attorney Pamela Johnston, the emergency-services conglomerate selected by San Diego Fire-Rescue officials — Falck of Copenhagen, Denmark — has a spotty track record unsuitable for San Diego.