Ron and Gwenda Bennett, from Verwood in Dorset, lost their £900 deposit on the £9,000 Mediterranean cruise which was due to set sail in September.
Voyages of Discovery, which runs the cruise, blamed the surcharge on rising global fuel costs and said it had followed industry rules issued by the Association of British Travel Agents.
It said there had been an “incredible and unanticipated” rise in fuel costs which had led to the surcharge to the Bennetts.
The firm said the couple were not entitled to a refund of their deposit as the surcharge was still less than 10 percent of the total holiday cost.
Under travel industry rules issued by ABTA customers are only entitled to a refund on their holiday if the surcharge is more than 10 per cent.
However, despite being £892 the Bennetts’ surcharge was under the 10 percent level by just £8.
Mrs Bennett said: “It was quite expensive to start with but with everything going up so much over the last 12 months we found it more and more difficult to rake the money together.
“The extra £892 was a bitter blow. They’re not breaking any rules but in principle I think it’s very poor.”
The couple were offered a shorter cruise or a smaller cabin on the 28-day trip which takes in Lisbon, Rome, Venice and Croatia, amongst other places.
But Mr Bennett said: “We wanted the best cabin we could afford for the whole month.
“I’ve heard of people being upgraded many times but never heard of anyone being downgraded.”
David Yellow, managing director of Voyages of Discovery, denied the firm was profiteering from its customers and blamed soaring worls oil prices.
He said: “The incredible and unanticipated increase in fuel costs has caused us much heartache and worry. The surcharges were applied as per the terms and conditions laid out in our brochure.
“While we understand that an additional bill of nearly £900 is highly unwelcome, we appreciate the Bennetts’ understanding of what is a worldwide problem.
“We travel to some amazing destinations and we have to buy our fuel en route at local market rates, often more expensive as a one-off annual purchase than a regular port of call would be.”
He said the firm was following the terms and conditions set out in its brochure and that passengers who book early for summer 2009 are being offered a “no surcharge guarantee”.
The firm said it hoped Mr and Mrs Bennett would reconsider the options offered to them and carry on with an amended holiday.