There does not appear to be any direct references to anti-slavery policies which are more substantive than general statements in this MSA Statement. While the Supplier Code of Conduct is referenced to, "with standards regarding human rights, working conditions, environmental protection and ethical business practices that E.ON requires its suppliers to meet;" (Page 2). It does not directly reference the incorporated policies within the MSA Statement, nor could I find the 2021 Supplier Code of Conduct.
"E.ON has a commitment to act ethically and responsibly in all its business relationships and has zero tolerance of slavery and human trafficking in any part of its business or supply chain." p.2
The statement also mentions they have an "E.ON Supplier Code of Conduct, with standards regarding human rights, working conditions, environmental protection and ethical business practices that E.ON requires its suppliers to meet" as one of the "internal policies, standards and processes in place groupwide to assist in tackling slavery and human trafficking" but it is not clear if this specifically covers modern slavery and human trafficking or more generally speaks of upholding human rights.