Several years ago, I had booked economy flights for my husband and I to go EDI-EWR-FLL. I was checking my booking online when one leg of the return journey disappeared so I phoned to query it and the agent said she would fix it and it would show online again in about 15 minutes. While I was on the phone, I queried how much it would cost to upgrade the EWR-EDI return leg and was told some outrageous amount. I immediately told the agent that it was far too expensive for me. However when I looked online next it was showing us in first class for the leg I asked about.
We kept waiting for the mistake to be rectified but it wasn't and we had a fantastic first class flight home - somthing we could never have afforded ourselves. The only problem is it has ruined travelling in economy!!