The South Australia state regulator fined six petrol stations nearly $20,000 for price breaches.
The inspectorate ran checks and found issues mainly around fuel price guidelines.
Customers were encouraged to call in if they spotted overcharging at pumps during the audit.
No brand names or location details were released yet.
Total fines total after recent patrol visits.
In Greater Western Sydney, Blacktown motorists now face higher for fuel than surrounding districts.
Regular pump checks indicate the area’s prices outpace other close competitors.
The difference means drivers there face higher costs per litre each time they fill up.
The gap has grown bigger than what regulators expect in normal regional swings.