Hi
The medicare levy is paid when you do your tax return annually, it will automatically calculate it online for you, so technically you do not hand over any payment, your refund will be reduced by the amount, if you understand my meaning, maybe somebody could explain it further for you. However in tomorrows budget, there is supposed to be an improvement in the medicare levy, so heres hoping!!
Also try
Private Health Insurance Australia - iSelect for health insurance comparisons.
Hope this helps