We have an award booking ( 2 people) which I would like to change to the following day. I am changing off-peak to off-peak days so can do it online. I have confirmed through a dummy booking that the seats are available.

I go into MMB and click the "change date or time of flight" option. After I tick the consent box to change both of us, a screen pops up,with 3 choices: no change, change time, and change date. I click the "change date" button and a calendar pops up, showing the date I want as available. I click that button and hit the red "confirm" button. The screen then reverts to the previous one and says I still have my original date.

I have tried this numerous times over the past 18 hours, always with the same result. Is this a temporary glitch? I have successfully changed reward flights online before, but that was several years ago. I know I could cLl, but I am not sure it is worth the long wait on hold to get one more day in London!