Delta Air Lines has been sued by passengers who complained that the airline refused to refund full fares after their flights were delayed or canceled as a result of last month’s massive computer outage.

The planned class action lawsuit was made public in federal court in Atlanta on Wednesday after the power outage on July 19 caused disruptions to airlines, banks, hospitals and emergency services.

The passengers accused Delta of breach of contract because the company did not provide automatic refunds and only granted partial refunds if the passengers signed waivers to assert further legal claims.

They also said Delta must compensate them for the costs and inconveniences associated with rebooking on other airlines, hotels and meals, and parting with their luggage.

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One of the four plaintiffs, John Brennan of Florida, said he and his wife missed a $10,000 anniversary cruise because they were stranded during a stopover in Atlanta, but Delta offered them only $219.45 in compensation.

The lawsuit states that the airline’s “unfair, unlawful and unconscionable practices resulted in Delta unjustly enriching itself at the expense of its customers.”

Delta declined to comment on the lawsuit but said passengers whose travel was impacted can request and receive a refund and seek compensation for incidental expenses (opens new tab).

Delta’s passengers were stranded and waited in lines for days to get to their destination,” Joseph Sauder, an attorney for the plaintiffs, said in an email. “When our clients demanded a refund, Delta once again failed to deliver.”

The outage was caused by a faulty software update from cybersecurity company CrowdStrike that crashed over 8 million computers worldwide and affected many Microsoft customers.

For many U.S. airlines, disruptions eased the next day, but for Delta they continued, leading to more than 6,000 cancellations.

Since then, CrowdStrike, Microsoft and Delta have been arguing publicly about who is to blame and should pay the bill.

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Delta CEO Ed Bastian estimated on July 31 that the outage cost his Atlanta-based airline about $500 million.

Passengers filed a separate class action lawsuit against CrowdStrike on Monday, also seeking damages.

The Austin, Texas-based company said it was neither negligent nor responsible for Delta’s problems.

The case is Bajra et al. v. Delta Air Lines, U.S. District Court for the Northern District of Georgia, No. 24-03477.

This article originally appeared on USA TODAY: Delta passengers sue airline for refusing refunds after technical failure