Athens pulled a scam on me one night by switching bowsers mid refuelling and eventually getting us to sign for nearly a ton more than delivered. Turned out they were selling it to executive jets passing through and paying cash for fuel! (We always checked the bowser counter before start but by changing mid way when we were not there the second bowser was arriving with the counter already showing at least a ton of delivery, being suspicious we caught them at it, it seems it was a big money maker for them!).