Settings menu is awkward at best, no clear user guidance on where to look at: once a phone number (which is the account number) is registered a reset of the account may only be done at their service station in Ulm. Registering of a payment method looks great, till the end, then nothing happens and you have to start all over. No matter what you try, you can't pay the ferryman, though the prices are specifically reduced for using the app. If Germans can't write software: just freaking buy it somewhere, where they can.