Sarasota's Grapevine Communications—an advertising, marketing and public relations agency—recently promoted three staff members. Britney Guertin, who has served as the company’s public relations and social media associate since March 2016, was named director of public relations and social media. Heidi Cook, formerly the agency’s special projects and events manager, was named director of operations. And Tammy Dumer, who joined the company in 2008 as bookkeeper, was named director of finance.