Dear Tripped Up,

In early January, my partner and I took a Holland America Line cruise in Baja California, Mexico. Months earlier, we had put our names on a waiting list for a $400-a-person whale-watching shore excursion that was scheduled for the fourth day of the cruise. Holland America confirmed our spot on the waiting list and told us that if spots opened up, it would notify us by email “on how to complete the purchase,” giving us 72 hours to do so. As the sailing date approached, we gave up hope and arranged a whale-watching trip on our own. But a couple of days into the cruise, we noticed that our credit cards had been charged $800 total when we boarded. We then found a note at our stateroom door (along with various announcements and coupons) explaining we had been booked on the excursion and instructing us to call or visit the shore excursion desk if we had made other arrangements. We went immediately, but the desk was closed. We returned the next morning, only to be told we had apparently missed a 48-hour post-purchase deadline to cancel. But the notice did not mention any deadline — and more outrageously, we had never agreed to the purchase in the first place! Appealing to the manager did not help, nor did a 53-minute call to guest relations after the cruise. Can you help? Gabriele, Oxnard, Calif.

Dear Gabriele,

I took a look at Holland America’s “Know Before You Go” page to see whether there was any related policy you should have, well, known before you went. There was a lot to take in: You can bring up to six liters of water on board with you, but no soda or energy drinks. Distressed jeans are not permitted in table-service restaurants. And more relevant, passengers are required to create an account to use for onboard purchases, and it will be charged automatically for a daily “crew appreciation gratuity” as well as for 18 percent tips on food, drink and spa purchases.

There’s no mention of charging your account for shore excursions without your approval, so I understand your exasperation.

But after hearing from Holland America and a cruise expert, I’d say the greater offense was the shore excursion manager’s refusal to back down by stretching the deadline a few hours — especially considering it was a deadline you had not been informed of, applied to a purchase you did not explicitly authorize.

Holland America quickly admitted fault on this last point and has now refunded you each $400. Guests who choose not to take an excursion in this situation are owed full refunds, and that should have happened when you made the request, said Jeanine Takala, a spokeswoman for the company, via email. “This was our error, and we apologize for the mistake,” she added.

Ms. Takala explained that your card was charged because once passengers board the ship, the cruise line uses a different system: charging them and then notifying them through the onboard Navigator app and stateroom letters, and in some cases by trying to call them, giving them a chance to cancel.