Pokerplex obviously isn’t the biggest operation on the Internet, so the support may not be as slick as at the bigger sites. But this bonus is certainly no scam, or at least it hasn’t been. I’ve have been playing Pokerplex for a little under half a year and have been receiving the bonus without fail.
I haven’t gotten around to clearing it this month yet, so I don’t know if this is just a problem with your account or a general problem.
Sorry I can’t be of more help. Have you tried the phone support? The numbers are on this page:
http://www.pokerplex.com/contactus.shtml