The South Australia state regulator fined six petrol stations nearly $20,000 for pricing violations.
The inspectorate ran checks and found issues mainly around charging standards.
Customers were urged to call in if they spotted overcharging at pumps during the inspection.
No company identifiers or location details were released yet.
Total fines accumulate after latest patrol visits.
In Greater Western Sydney, Blacktown motorists now pay more for fuel than adjacent areas.
Regular pump checks indicate the area’s prices outpace other nearby spots.
The difference means drivers there face higher costs per litre each time they fill up.
The gap has grown bigger than what regulators predict in normal regional swings.