LONDON — Vindi Banga, Unilever’s president of global foods and home and personal care, will leave the company in May. He has worked for the firm for 33 years. Michael Polk has been named Banga’s replacement. Polk is currently Unilever’s president, Americas. Dave Lewis, executive vice president of Unilever, U.K. and Ireland, is to succeed Polk in that role. Lewis will also join Unilever’s executive board.