Purchasers of travel insurance are finding their policies all but worthless as the global pandemic forces them to change their plans, or worse, leaves them sick at sea.

Most travel insurance companies won’t provide reimbursements for canceled trips due to the coronavirus, according to New York’s Department of Financial Services. In addition, some insurers flagged Covid-19 as a “known event” in January, meaning policies bought after that won’t pay out due to virus-related interruptions.

Allianz SE, the German insurance giant that is one of the largest sellers of policies, said it is accommodating claims from customers who become ill with Covid-19 either before or during their trip. That could include providing compensation for a canceled trip or emergency medical care on one.

But many consumers say their claims have been denied, and they’ve taken to social media to complain.

The parents of Jih-Hao Cheng, a lawyer from Southern California, had planned for a year to go on Holland America Line’s cruise to explore South America. When coronavirus struck, he asked his parents if they should reconsider. His dad, Min-Lee Cheng, a public health administrator, said he trusted the cruise line to cancel the trip on the Zaandam if passengers’ safety was at stake.

Still, the couple purchased travel insurance from Allianz that includes emergency medical evacuation and repatriation just to be safe. Little did they realize they would be in need of it.

A day after they boarded the vessel on March 7, the U.S. State department advised Americans not get on a cruise. Then Chile refused to allow the ship to dock, while Peru, Ecuador and other destinations on their route closed their ports. About two weeks into their voyage, Cheng and his wife, Shou-Yinn Cheng, both came down with fever. By then, the entire ship was under quarantine, and the couple and all of the passengers were forced to stay in their cabins. Four passengers died, while nine would become infected with Covid-19 by the end of the trip.

Back in Southern California, their sons worried. The couple recovered from their fever, but their father became more lethargic and didn’t eat. “We were concerned his immune system and health were compromised,” said one son. “He wasn’t getting better, and the medical staff on board were too overwhelmed to give him attention. They were low on medicine.”

Cheng called up Allianz to try to get a medical evacuation for his parents. The agent brought up clauses they weren’t aware of. The coverage would be waived in the case of a pandemic or if the event was “foreseen,” he was told. The agent pointed out that coronavirus had plagued other cruise ships, which attracted global media attention, before the couple began their cruise.

“They were essentially denying the claim,” Cheng said. “These ship insurance policies are a total scam. They’re shirking responsibility.”

A spokesman for Allianz said the company would look into the matter. On Thursday, the Zaandam finally docked in Fort Lauderdale, Florida, proving what may be an exit for the Chengs.