this account was never sold or bought. You can google the
username there are dozens of forums profiles, accounts, transactions, all managed by one company (domainmagnate.com). It is very easy to verify and confirm by simply searching around a bit. If there are any mods reading this please review this, and reply below or contact for any clarifications.
From our investigation it seems the employee who was tasked with managing this account opened a thread selling some account - he couldn't be selling this one because he didn't have the rights to it - perhaps he was trying to sell a different one. He no longer works for the company since last year.
Even if what you claim is true, nothing can be done. You as a company are responsible for your employees' actions. The fact remains that your account, regardless of whether it was an employee posting at that time, made a thread selling an account which led to negative trust.