Worst app ever

This app is beyond CRAP. Every time I enter my reservation number, it gives me an error. If I try via the mobile website, it works, but then to get my boarding pass it says to first log in via the app. Guess what? That doesnt work! I get the same error as in the beginning. How can you be a billion-dollar airline and have an app that doesnt even work well enough to let you get your boarding pass?!

T-Bone SDC about British Airways, v5.15