I would see no point in using a helpdesk in a control panel!
if you had multiple control panels ie cpanel for linux, dnp for windows etc you'd end up with several helpdesks which is totally silly and unprofessional.
You should have a single helpdesk such as whmcs, kayako or smartertrack where your customers can go to submit ticket, what if the ticket was that the control panel is down? your client would not be able to submit a ticket... or maybe you've suspended the client for none payment.. again they would not be able to login to submit a ticket.