Okay so I came across this really nice Hosting site, I'm sorry guys I will not display the URL if you wanna know it, please pm me and I'll send you the url. But anyways I just thought that their billing system integration is so organized and I like the way it looks I been trying to find out what billing system they are using something tells me that they are using WHMCS but I don't know It might also be Clientexec take a look at the screenshots below and tell me what you guy think this billing system is. Thank You, Richard.
Almost certain it's WHMCS. If you want to be completely sure, send me the url via private message and I will verify.