Karim Ghazzaoui, the owner of Global Flights in London, said the problems arose after his agency booked 18 tickets for a group travelling in February last year.

However, the Air India flights, which were booked via Worldspan, were ticketed using the Aeroflot plate after he claimed the GDS gave the wrong guide issuance to the agency to do so.

And now, nearly a year after the trip, the agency has received a total bill of £56,178 from Air India for the 18 tickets that Ghazzaoui believed had cost £508 each. He has been given until March 17 to pay.

While Ghazzaoui admitted he would be happy to pay an ADM charge of between £25 and £50 a ticket that many other airlines charge, he is worried that paying the full charge would put the agency, that has been trading for more than 20 years and has two other employees, out of business.

He said: “If Air India didn’t want to accept these tickets they could have said they were wrong [at the time].

“I won’t be able to pay the airline and it is a killer situation. I’d close my business, it is logical. I haven’t defrauded them, I made a mistake because Worldspan was giving the wrong message.

“All we are trying to do is avoid everybody from going to the lawyers.”

A spokesperson for Air India said the problem had been brought to the attention of the regional office in the UK.

She added: “We’re looking into it and hopefully we’ll get a favourable reply from head office.”