The editor wrote to the authors stating that if they insist on a withdrawal at this stage there would be three sanctions: 1) they would be blacklisted (ie, none of the publisher’s journals would consider future submissions from any of the authors, 2) the journal would write a letter to the superiors of the authors outlining the case and 3) they would still be responsible for the Article Processing Charge which is payable on acceptance; ours is an open access journal, with the fee schedule clearly disclosed and agreed upon by the submitting author (the fee schedule specifies that if the paper is withdrawn after acceptance it is still payable and will not be refunded).