margin call hell tomorrow, page-56

MikeMennell, a quick question for the uneducated (me):

What do you mean "the margin call for OZL has been increased by 75%" by your CFD provider and so "CFD traders will have to stump up an extra 75% just to hang onto their OZL shares"?

I understand vanilla bank margin lending (say I own $100,000 of shares, they will loan me another $75,000) but what do you mean the margin call has increased by 75% and why is it negative for OZL?

Thanks for your time and patience.