The river line confirmed it had apologised to customers whose holidays "fell short of the standards we aim to deliver", after passengers on Tui Skyla reported persistent problems with air conditioning while the vessel was in Budapest during a heatwave.
Tui River Cruises said the problems affected a number of sailings on both Tui Skyla and Tui Isla, with "various unexpected technical issues" affecting air-conditioning systems.
According to the BBC, dozens of customers have accused the company of "operating vessels with faulty facilities including persistently broken air conditioning".
