U-abo payment: orange slip or machine?
I have a U-Abo card since March. I have always been buying my monthly ticket from the ticketing machine. However, for July, I received a bunch of orange slips for the rest of the year's payment. My question is: can I ignore the orange slips and just keep buying from the machine? I find it more convenient. If I understood it correctly, even if I pay using the orange slip online, I still have to have my receipt stamped. Therefore, I need to visit the TNW office to get this (or pay the orange slip at the post office).
Any advice? I will be flying out of the country today and when I come back it's already July and I want to be able to use my U-abo ticket to travel back home from the airport.