The South Australia government agency fined six petrol stations nearly $20,000 for pricing violations.
The watchdog ran checks and found faults mainly around charging standards.
Customers were urged to call in if they spotted price inflation at pumps during the inspection.
No brand names or addresses were released yet.
Total fines total after latest patrol visits.
In Greater Western Sydney, Blacktown motorists now spend extra for fuel than nearby suburbs.
Regular pump checks indicate the area’s prices sit above other local stations.
The difference means drivers there pay extra per litre each time they fill up.
The gap has grown bigger than what regulators expect in usual regional swings.