"Speak Up Policy, Respect and a culture of openness in the workplace is a key aspect of the Marsh McLennan ́s Code of Conduct. Mercer encourages colleagues and other business partners to report any concerns, including any concerns relating to modern slavery or human trafficking. Mercer’s speaking up procedure, utilises an Ethics & Compliance Line (a service administered by third party) which makes reporting easy and confidential." - Mercer Modern Slavery Statement 2021, Page 2
There is no mention of any grievance mechanism for supply chain.
pg. 2
"Colleagues are encouraged to report any concerns or suspicions regarding the presence of modern slavery within the supply chain."