CCTV images of missing South Australia woman Colleen South have emerged at a Calder Highway service station.

The footage was captured about noon on July 3, the last day the 58-year-old was seen.

It shows the grandmother attempting to pay for fuel at Sunraysia Petroleum's self-serve Shell service station at Berriwillock.

The ABC, which spoke to a member of Ms South's family who has seen the foot...