Rebecca Rhodes left last week without a new job lined up.
Corporate director Paul Maguire and creative director Claire Mann left in the summer, with no roles lined up.
CEO Fiona Noble said the resignations were 'part of the natural change in a company'.
In addition, PRWeek reported in August that deputy MD Caroline Maddock had left after taking maternity leave. She then joined Chandler Chicco Agency as team leader. The resignations follow a C&W merger with GCI last year.
