Well, I took a punt and went to www.octagon.com
and lo and behold! that was it
Anyway, if you go there, there's a menu for selecting the country you want and if you go to Octagon-Australia, there are lists of athletes (has anyone heard of a tennis player called Patrick Nicholls?!) and a "contact us" section. I have heard the name Justin Cohen so I picked the Melbourne address. I suggest writing here.
123 Moray St
South Melbourne VIC 3205
t +61 3 9685 3500
f +61 3 9686 6660
Justin Cohen – Athlete Sales & Marketing Manager