I recently tried to buy a Monatskarte with my credit card and thought it would be wise to document the process for future travellers. Buying a monthly public transit ticket is a simple, painless process in Berlin.
1. Walk to the nearest U-Bahn or S-Bahn station, and find a ticket machine.
2. Among the 30+ ticket options, select the one that matches your desired use.
3. Insert your credit card in the slot when prompted to.
4. Get a message saying that this terminal does not support credit cards, only EC cards.
5. Repeat steps 2, 3 and 4 with every ticket machine in the station, only to have your expectations of modernity further crushed by the BVG.
6. Walk to the nearest ATM and withdraw 100 euros. Accept the 5 euro fee.
7. Return to the ticket machine with your money in hand and select your ticket again.
8. When you reach the payment screen, realize that the machine won't accept the 50 euro bills the ATM gave you.
9. Walk to the nearest späti and get some change for your 50 euro bills. Reward the gesture by purchasing a candy bar and a Club Mate.
10. Return to the ticket machine with your money in hand and select your ticket again.
11. Wait for the ticket and the receipt to be printed.
12. Voilà! You have your ticket! Enter the next train. Prepare excuses for being 25 minutes late.