Staff from Thomas Cook are to hold protests at this week’s Tory party conference in Manchester and later at Downing Street over the government’s decision not to step in and save the company from liquidation.

Staff were due to get their monthly salaries on 30 September but are instead among Thomas Cook’s creditors, and it is now unclear when they will be paid. Some 150,000 UK holidaymakers are being repatriated at taxpayers’ expense following the demise of the world’s oldest tour operator. On 28 September, a further 16,700 customers were set to be flown home.

Hundreds of employees of Thomas Cook Airlines are expected to gather at the conference on 30 September to express their anger. “They won’t be overly political but they feel abandoned by the government,” said a spokesman for the Unite union.

A group of workers will then travel to London to protest outside 10 Downing Street on 2 October. Among them is former cabin attendant Emma Boxen, who learned of the collapse via social media. She is owed over £2,000 in pay but says she has not received any official communication from the company. “I can’t afford my mortgage. I have all of my bills to pay. It is just horrible,” she said. Online funding pages are being set up to help former employees with the cost of travel to London, she added.

The business secretary, Andrea Leadsom, has been accused of acting far too late after she set up a taskforce to help those affected. The parliamentary business, energy and industrial strategy committee has announced an inquiry into the role of “corporate greed” in the collapse, focusing on directors’ stewardship of the firm, their pay, and the role of auditors.

The collapse of Thomas Cook is likely to wreak havoc on tourist industries around the world, and nowhere more so than Greece, where locals considered the company too big to fail. Manolis Giannoulis, head of the hoteliers’ association in Chania, Crete, said: “It was the second-largest tour operator in Europe. Falling like this proves that anything can happen. The damage is huge, probably in the region of €80m – and that’s only here,” he added. “It’s almost like a national crisis, coming just as our economy is returning to normality.”

Over half of Crete’s 2,000 hotels worked with Thomas Cook, and the insolvency left 20,000 customers stranded on the island.

Tourism accounts for 25% of Greek GDP and one in five jobs. Britain’s biggest holiday operator to Greece, Thomas Cook flew in 3 million visitors a year, and employed more than 1,000 people on the ground. For Michalis Vlatakis, president of Crete’s travel agents’ association, the firm’s liquidation resembled an “earthquake” that would inevitably send a tsunami through the economy. “It’s not only the contracts that are lost, but all those that won’t materialise,” he said.

Further north on the Aegean island of Skiathos, where Thomas Cook flew 40,000 passengers in the past year, the impact is “just massive,” according to Thodoris Tzoumas, mayor of the island that shot to fame as the setting for the 2008 film Mamma Mia! “I don’t think I can convey how big it is.”

As in Crete, hoteliers on Skiathos were owed three months’ payments by the company in what was peak season for the sector. Officials estimate losses of up to €500m countrywide – a staggering amount for a debt-stricken nation.