Shocked tourists told to pay twice

And the Civil Aviation Authority (CAA) warned that Sun4U-booked

travellers arriving overseas may find their airport transfers and

booked accommodation unavailable to them.

The Birmingham-based company ceased trading on Wednesday night with about 1,200 UK holidaymakers abroad, mostly in Spain.

Some of these are covered by the CAA-run Air Travel Operators'

Licensing (ATOL) scheme and will be able to carry on with their holidays and travel home.

But Sun4U also organised flight-only and accommodation-only trips which are not covered by the Atol arrangement.

Also, the CAA said that even if holidaymakers' trips were Atol-covered, "hotels and accommodation agents may require customers who are abroad on holiday to pay again for their accommodation".

The CAA said that Atol-covered holidaymakers would be able to claim this money back.

Mother Patricia Cambridge said her daughter had been asked to pay again for her half-board holiday.

She said: "She was told that they would have to pay 438 for the self-catering holiday, plus 10 euros (8) a day if they wanted half-board.

"They'd actually booked a half-board holiday and paid Sun4U for that holiday."

The CAA advised those Atol-protected customers who find their airport transfer and accommodation has become unavailable to make their own arrangements and then send a claim to the CAA.

A spokeswoman said yesterday: "We understand there are around 1,200 people abroad and we are trying to find out just how many are Atol-protected.

"We are also trying to determine just how many people have forward bookings with Sun4U.

Kellie Bugby was due to travel to Majorca in two weeks' time with Sun4U along with 36 relatives.

She said: "We've tried the website, we've tried calling. We're still a bit lost about whether we are or aren't going.

"It's something we've been planning for a whole year. It's over 12,000 of money."

Ms Bugby, from Leicester, said she checked the Sun4U website three days ago and the company appeared to be still selling holidays.

She added: "They must have known that the ones they were still selling weren't going to go through. It's so unfair."

Meanwhile management and unions locked in a bitter airport workers' pay dispute will meet at conciliation service Acas on Monday in a bid to stop a strike that could hit millions of people.

Ground staff workers, represented by union Unite, at six UK airports run by BAA, including Heathrow, have voted three to one to strike.

The Unite workers include firefighters and security staff, with Unite saying that BAA faces a "total shutdown" at the six airports – Heathrow, Stansted, Southampton, Glasgow, Edinburgh and Aberdeen.

But Acas has offered to hold talks and yesterday it was agreed that these discussions would take place on Monday.

Any strike action will have a huge effect on bank holiday travel at the end of this month.

Air travellers have already been hit this year by the Icelandic ash-cloud crisis and by a series of strikes involving British Airways' cabin crew who are also members of Unite.

Prime Minister David Cameron and Transport Secretary Philip Hammond have both spoken of the damage that would be caused to businesses, jobs and tourism if a strike went ahead.