Worth noting that some travel agent will sell you consolidator fares at full price.

I had a case on HFP where Amex, of all people, did this to someone on a Delta flight where the reader needed the miles for status and didn't get any.

Eg: Delta (or whoever) is selling a flight for £3000

Agent has access to a £1750 consolidator fare

Agent marks up the ticket to £3000, making a cool £1250 on the sale, and you think you have bought a standard ticket - but you haven't