This story up to now was hot as hell, but without a too-deeply-developed plot. The last two chapters were a complete surprise, and are brilliant!
There are unfortunately two main holes that you leave open:
First Holms is certain that Mallory and Ellis (pus a third unknown) are plotting against Meridon and gives as proof the mail exchange. However, the content of the mails is completely omitted (apart the distracting detail that they are hot) and the reader is completely in the dark about the issue they are plotting about.
Second: Holms plan to catch the "bad girls" is poor. Given the high knowledge those bad girls have of Meridon Security System, they knew from the beginning that the cloned bracelet they created would have been tracked. To keep the girls confident that their plot was not discovered, it would have been much smarter to fake an arrest & exemplar punishment of Warden herself. Then, another private office with a computer able to modify bracelets ID and priviledges had to be left open as a trap for them.