This announcement may not come as much of a surprise since Air Berlin has been having financial difficulty for a while now. Per this announcement (which doesn’t really give customers that much notice) long-haul flight operations will cease by October 15th. See the announcement for more information. 

Air Berlin Ceases Long-Haul Flights 10/15

airberlin will need to cease its long-haul flight operations by 15 October 2017, as the aircraft leasing companies are gradually withdrawing their Airbus A330 jets. The connection between Dusseldorf and Los Angeles will therefore be discontinued on 25 September 2017. Further cancellations will follow on 16 October 2017. On 29 September 2017, airberlin will discontinue services between Hamburg and Munich and between Cologne/Bonn and Munich. We regret the inconvenience for our passengers.

My long-haul flight has been cancelled. What happens now?
All airberlin passengers will be informed of the status of their booking. This will be in the form of either a cancellation confirmation or a rebooking confirmation. Passengers for the affected flights will be rebooked on alternative flights wherever possible. Whether or not your flight can be rebooked will depend on the availability of alternatives.

For passengers who booked their plane ticket directly with airberlin, the following applies: for tickets purchased after the insolvency filing on 15 August 2017, we will reimburse the purchase price free of charge. Passengers affected may submit any additional costs incurred via the website www.airberlin.com/complaint. Tickets that were booked before the insolvency filing cannot currently be reimbursed due to insolvency regulations.

Bottom Line

If you have any issues getting a refund, I would definitely contact your credit card company to dispute the charge. I have had great success disputing charges on my American Express card/s.