Based on my understanding
Margin is widely used by broker to give loans/$$$ to some individual mostly the shareholder to buy the share by borrowing money from the broker ..
If your account falls below the firm's maintenance requirement, your firm generally will make a margin call to ask you to deposit more cash or securities into your account. If you are unable to meet the margin call, your firm will sell your securities to increase the equity in your account up to or above the firm's maintenance requirement.
Always remember that your broker may not be required to make a margin call or otherwise tell you that your account has fallen below the firm's maintenance requirement. Your broker may be able to sell your securities at any time without consulting you first. Under most margin agreements, even if your firm offers to give you time to increase the equity in your account, it can sell your securities without waiting for you to meet the margin call.
So when, there is something not right, or the broker want to take back the loan/reduce the margin , they will send a call margin to the individual saying, do you have enough fund to cover the margin , else the broker will then no choice will force sell the share and get the money from the share market.
Exp Broker A give u margin of 5 million , and broker A want to reduce your margin to RM2 million .. means the individual need to pay back the broker A RM3 million either in cash , mortage in certain period of time , else, the broker will force sell the share and get the money $$$.
As you see now, why the price still hanging around 0.07 - 0.08 for 2 weeks because the broker are not stupid, they also want to maximise the return selling the share ... if they dump in big bulk to fast .. the share price will go to 0.01 ...
In Compugates case, I believe, margin call is just a charade to disguise the overall plan. Numbers don't add up.