Tried to make a change to the return leg of an existing US-Europe roundtrip booked with miles. App came back with a shockingly low price (and taxes quoted in GBP - this trip has nothing to do with the UK). I tried making the change but it errors out, claiming I’m logged into the wrong account. I am not.

Checked on the website, there is no such fare available (it was less than half of the originally booked price). So the app is quoting something completely wrong and unrelated to my search.

Great job testing that app, Delta IT. Only the best.