Also for some reason you cannot buy an ABC ticket on the app. Twice when I’ve arrived at the airport been forced to use the ticket machines.Edit: I got a reply from the developer and apparently you can change the fare zone in order to buy an ABC ticket. This app needs improvement with UI and Ux if a user whose has purchased tickets with the app since it’s first released didn’t clearly understand how to access that feature. To clarify I was trying to use my four pack of AB tickets to buy a ticket into berlin from the airport , it did not work. (most likely because BER is in C.) Did I need to buy the C ticket first and then activate the AB ticket? Could the app tell me the next step instead of just locking me out ?
Edit 17.03.2023: Hi, it is correct that you cannot activate a section of an AB ticket in the C area with a C station and we do not advise to activate a section of an AB ticket and to buy an extension ticket in addition, as this is more expensive than buying either a single trip ticket ABC or, if you use the tickets more often a 4-trip-ticket Berlin ABC. --- Hi, that is not correct, you can buy ABC tickets with the app ;-), you need to choose the ticket you wish to buy and then click onto the field "fare zone", a pop up opens at the bottom of the screen where you can change from AB to BC or ABC.