I guess I should have looked up what the Jordan Ultima was before making a suggestion. I was imagining it was a shore power cable of some sort you were talking about...though strangely the question and advice were not too far off.
It looks, from pictures online, that the cable from the brake pedal to the controller (which I think may be what you're talking about) is basically just a fairly standard wire rope or aircraft cable of relatively small size. The tricky part of replacing it may be getting an appropriate fitting for the controller side of things.
(If it's the electrical harness you're talking about, then just splice in some new wires and call it a day.)