Emma, this question is designed to test your knowledge of "negation". Just as in French, in English there are rules governing "negation".
"Do not ever accept..." is correct. "Never accept ..." is correct. "Do never accept..." is not correct.
As Ed has pointed out, when you start with "Do", you have to go "Do not ever ..." You cannot do "Do never ..."
"The imperative and the rules of negation" - that would be the chapter in the grammar book for this topic.