Pollination is essential. Check to see what the area has pollinating insects like bees, butterflies or flies. The insects may not be out in full force considering that it is winter, but you would know better than I. If you are fairly certain that you have active pollinators, water may be an issue.
If the plant does not have weekly deep watering, the flowers will drop. Make sure that the soil is wet at least 6 inches deep. Mulch to preserve moisture. Water deeply on a weekly basis, more if the climate is dry.
If you have both pollinators and adequate moisture, you could always try pollinating by hand using a fine paintbrush or some cotton swabs. Just lightly transfer pollen from the flower of one plant to the flower of another. Let us know what happens. Often wnd can be a good enough pollinator for these plants. (If there is enough wind)
I think as spring starts to arrive and things warm up, this plant will take care of it self.. (patience)