If you feel someone is using an engine in games then you should report them.
https://support.chess.com/customer/portal/articles/1444879-cheaters-cheating-what-you-need-to-know
the link to report is in that article. The site doesn't allow discussions of cheating in the general forums (it is really counter-productive). For that, use the following: http://www.chess.com/groups/home/cheating-forum
Is anything being done about players using engines here on chess.com? I just called one out who clobbered me in our fist game but I blew away in the second. he was rated 100pts. above me. I have had this annoying feeling for a while. I was planning on becoming a diamond member because I desperately want to improve my game (it sucks) but I am wondering whether playing here is really worth it. Thoughts?