Ali Shah, chief executive of Travel Up, said more than 2,000 of his customers had been affected by the blunder, which saw BA flights to Dubai and Tel Aviv advertised at bargain prices.
The tickets are believed to have been sold over June 11-12. BA has apologised, refunded customers and offered them a £1,000 ticket voucher.
However, the airline has not yet revealed exactly how many flights were sold “incorrectly”, save for stating the fares were available to a “small number of agents over a short period of time”.
Shah, the BBC reports, said flights that usually cost between £200 and £300 were being advertised for £1 plus airport taxes, raising the price to levels that while cheap, many claim were not manifestly under-priced.
While BA has cancelled the tickets, there could yet be legal repercussions if a passenger was to challenge the airline’s decision.
BA would have a defence if the tickets were sold at a price so low the mistake would be evident to anyone trying to book.
Passengers though variously claim having bought tickets for up to and around £200, far from being excessively cheap and near the typical cost of a flight to Tel Aviv.
TTG checked fares for London departures to Tel Aviv over the week of September 4-11 and found the cheapest tickets starting from around £150 and the dearest £370, with the average being around £200 to £225.
Airlines generally honour mistake fares, with cancellations only for blatantly incorrect prices, placing the BA situation in a grey area.
A BA spokesperson said: "The fare was only available to a small number of agents over a short period of time, so only a small number of our customers have been affected.
"We have apologised and offered a gesture of goodwill. Errors like this are exceptionally rare, and if they do occur, under contract law, there is no binding contract between the parties."