Travel agents acted swiftly to rebook clients after the British Airways IT glitch that left more than 75,000 passengers were stranded at Heathrow and Gatwick and hundreds of flights cancelled or delayed at the weekend.

Passengers were forced to queue outside Heathrow Terminal 5 or to leave the airport without luggage even as things got back to normal.

Business and leisure agents chipped in over the  bank holiday to get their passengers back on track, or help them with compensation claims.

Steve Murray, head of Focus (corporate travel) operations at Advantage Travel Partnership said: “Lots of our guys were busy over the weekend. There was a lot of rebooking and so little information from BA. The trade sorted passengers out – best of luck if you booked on Ba.com.”

Paul Smith, owner of WOT Travel in Twickenham, had five clients booked on BA flights on Saturday, including one due in Singapore on Monday. Smith said BA “pulled the shutters down” amid “utter chaos” at Terminal 5. He called TravelPack homeworker Dave Brammer, who booked a replacement Qatar Airways flight to Singapore which arrived around two hours later.

Smith said: “It would have soothed things if BA had kept people updated.” He found replacement flights for his other clients and said he would be seeking compensation for all of them.

BA had a special message for the trade amidst the fallout from the system failure, which it put down to a power outage.

A spokeswoman told Travel Weekly: “We’re extremely sorry for the frustration and inconvenience our trade partners experienced over the Bank Holiday. We would like to thank them for their tireless efforts supporting us during the disruption.”

Earlier, BA chef executive Alex Cruz told the BBC he was “profusely sorry”. However, there were calls for Cruz to resign from some BA staff. Others accused management of “poor visibility” and “poor communication”, while the GMB union blamed the IT meltdown on BA axing 700 IT jobs last autumn.

BA blamed a power outage. Cruz said: “There was a power surge and a back-up system did not work. We will make sure it doesn’t happen again.”

A BA spokeswoman said: “It was a power supply issue at one of our UK data centres. An exceptional power surge caused physical damage to our infrastructure and many of our operational IT systems failed. We’re undertaking an investigation to find out the exact circumstances.”

But GMB national officer for aviation Mick Rix said: “This could have been avoided. BA made hundreds of IT staff redundant in 2016 and outsourced the work to India.”

US carrier Delta Air Lines suffered a similar systems malfunction last August when a power surge brought down is reservations system. Airline IT experts say it’s an increasingly common problem due to airlines adding ‘a patchwork’ of new technology integrations to decades-old reservations systems.

Aviation analyst Chris Tarry told Travel Weekly: “This hasn’t been good from a PR perspective. The BA premium brand may suffer a little. You can’t just cut costs to maximise revenue.”

Later in the week, IAG chief executive Willie Walsh defended BA’s handling of the situation and backed Cruz.

And, in his first public appearance since the incident, he dismissed claims that the problem was down to BA outsourcing to India, adding: “We know the cause of the problem. It was not about IT. The problem was caused by the failure of electricity power to the IT systems.”

British Airways is still investigating, but its contractor CBRE – which manages facilities at BA’s Boadicea House data centre near Heathrow airport – denied human error had played a part.

“We understand what happened but are investigating why and that will take some time,” Walsh said.