their phone numbers are listed. i would just call ahead.
So you've received an offer for 10 cents off and there is no simple method to find where they are, and in our case there are none within at least a 10km radius?
Is that a 'true' offer or a bait offer designed to mislead/lure customers into a transaction with no hope of receiving the advertised benefit?
With your solution you first have to find a list of Caltex stations, then find their respective phone numbers and then you have to spend time ringing them until you find one that does not have a Star Shop or Star Mart. After the first 4 - how many more should you reasonably be expected to keep ringing?