Saying they felt poorly treated in their volunteer roles, two members of a town body that oversees the New Canaan Department of Human Services on Thursday resigned from their positions. Judy Dunn, a member of the Human Services Commission since 2010 and its chair for the past five years, said in a letter read aloud at the appointed body’s regular meeting that First Selectman Kevin Moynihan had acted inappropriately in selecting the nine-member body’s next chair himself. Because the Commission had a quorum, the first selectman also had been incorrect in January to postpone an organizational meeting for the body to elect its own chair, Dunn said in her letter, and wrongly asserted that Commissioner Renate Dolphin should resign for missing meetings. “Mr. Moynihan said Renate Dolphin had missed three meetings and should be asked to resign,” Dunn said in the letter, read out by Commissioner Alicia Meyer. “He said I should ask her to resign.