British Airways pilots are planning a strike for three days in September, and flights are already getting disrupted.

According to emails received by passengers, flights between Sept. 8 and 12 are being canceled, forcing travelers to rebook or seek a refund. Strikes are planned to take place on Sept. 9, 10 and 27. The strike is in response to pay disputes between the airline and the British Airline Pilots Association (BALPA) union, according to the BBC.

There has also been confusion about whether flights will happen or not. After receiving the initial cancelation email, some travelers then receive another message explaining that their flights are going ahead as scheduled.

Many more are also reporting great difficulty in reaching out to the airlines to make alternative plans. British Airways have acknowledged and apologized for these troubles.

“Our teams have been working tirelessly to help as many of our customers as possible, in these unprecedented circumstances,” British Airways said in a statement. “Our planning teams have been providing our customers with as many options as possible, as quickly as possible, including a full refund or rebooking to a different date of travel.”

BALPA has stated that these strikes are a “last resort” measure to overcome pay disputes with the company's management. The union claims that the airline has rejected numerous options to resolve the issue, with two parties’ proposals currently having a $6.1 million (£5 million) difference. Approximately 93% of BALPA’s members voted in favor of a strike.

“Over recent years BA pilots have made sacrifice after sacrifice to assist the company such as taking a pay cut, productivity increases, closing the final salary pension scheme, giving up annual leave days, a new rostering system, and reducing flying pay,” BALPA said.

British Airways
This photo shows an Airbus A320 of British Airways as it flies above Toulouse, southern France, Aug. 27, 2018. Getty Images/PASCAL PAVANI