OK went to a hydraulic hose place today (Pirtek) and the guy behind the counter knew all about the hoses on the self levelling suspension. It took 1.5 hours and $100aud and I had a new hose.
I was over joyed as MB quoted me $715aud for the hose.
Unfortunately after fitting the new hose the car now has a buzz or vibration at 2000-3000rpm and I think it's from the new hose.
Moral of story buy genuine when that's all there is, as there's probably a good reason.