David Mallon and a group of five others were due to travel on 21 September. But they decided the new itinerary presented to them a few days before departure was so different from what they had booked that they didn’t want to go.
“What they were planning to give us was not a cruise but a glorified coach trip,” says David.
One reason for not wanting to accept the new plan was that a member of the group was meant to be avoiding long periods of sitting down – such as coach journeys – for health reasons.
With no offer of a refund, the group booked a last-minute holiday to Kos instead and decided to try and claim money back on their return.
“We don’t blame Tui for the water levels, but it’s the way they’ve handled the consequences of that,” David says.
He has now submitted a complaint to Tui and says he will take his quest for a refund to the small claims court if necessary.
The BBC contacted Tui River Cruises about passengers’ unhappiness with the extensive itinerary changes and the fact they were not offered any refund.
In a statement, a spokesperson said: “Extreme heat across Europe this summer caused low water levels on the Danube, affecting river cruise operators across the region. We review every sailing individually with our nautical partners.
“Customers on the Tui Isla departures on 14 and 21 September were sent revised itineraries before travelling. Where the ship couldn’t sail sections of the river, we arranged coach transfers, hotel stays and adjusted travel arrangements to minimise transfer times so customers could still visit destinations, including Budapest, Vienna and Bratislava.
“We reviewed the revised arrangements carefully and customers continued their holiday on the amended itinerary under our standard booking conditions. While customers were still able to visit the key destinations on their itinerary, we’re sorry some did not get the river cruise experience they had anticipated.”