Claiming unavailability of 93

In the past two weeks my husband and I have experienced that Engen claims to be 'out of' 93', and insisting on filling up with 95, which is the costlier option. When confronted, the first agency was prepared to refund us with the difference. Today, at another station, while the petrol attendant said that no 93 was available, another car was being filled with 93 at the pump in front of us. We spoke to the manager, who first rep**** that there was no 93 available