Bangkok's showcase new international airport is no stranger to controversy.
Built between 2002 and 2006, under the governments of then-Prime Minister Thaksin Shinawatra, the opening date was repeatedly delayed.
It has been dogged by allegations of corruption, as well as criticism of the design and poor quality of construction.
Then, at the end of last year, the airport was shut down for a week after being occupied by anti-government protesters.
Now new allegations have been made that a number of passengers are being detained every month in the duty free area on suspicion of shoplifting, and then held by the police until they pay large sums of money to buy their freedom.
That is what happened to Stephen Ingram and Xi Lin, two IT experts from Cambridge, as they were about to board their flight to London on the night of 25 April this year.
They had been browsing in the duty free shop at the airport, and were later approached by security guards, who twice asked to search their bags.
They were told a wallet had gone missing, and that Ms Lin had been seen on a security camera taking it out of the shop.
The company that owns the duty free shop, King Power, has since put the CCTV video on its website, which does appear to show her putting something in her bag. However the security guards found no wallet on either of them.
Despite that, they were both taken from the departure gate, back through immigration, and held in an airport police office. That is when their ordeal started to become frightening.
"We were questioned in separate rooms," Mr Ingram said. "We felt really intimidated. They went through our bags and demanded that we tell them where the wallet was."
The two were then put in what Mr Ingram describes as a "hot, humid, smelly cell with graffiti and blood on the walls".
Mr Ingram managed to phone a Foreign Office helpline he found in a travel guide, and was told someone in the Bangkok embassy would try to help them.
The next morning the two were given an interpreter, a Sri Lankan national called Tony, who works part-time for the police.
They were taken by Tony to meet the local police commander - but, says Mr Ingram, for three hours all they discussed was how much money they would have to pay to get out.
They were told the charge was very serious. If they did not pay, they would be transferred to the infamous Bangkok Hilton prison, and would have to wait two months for their case to be processed.
Mr Ingram says they wanted £7,500 ($12,250) - for that the police would try to get him back to the UK in time for his mother's funeral on 28 April.
But he could not arrange to get that much money transferred in time.
Tony then took them to an ATM machine at the police station, and told Ms Lin to withdraw as much as she could from her own account - £600 - and Mr Ingram then withdrew the equivalent of £3,400 from his account.
This was apparently handed over to the police as "bail", and they were both made to sign a number of papers.
Later they were allowed to move to a squalid hotel within the airport perimeter, but their passports were held and they were warned not to leave or try to contact a lawyer or their embassy.
"I will be watching you," Tony told them, adding that they would have to stay there until the £7,500 was transferred into Tony's account.
On the Monday they managed to sneak out and get a taxi to Bangkok, and met an official at the British Embassy.
She gave the name of a Thai lawyer, and, says Mr Ingram, told them they were being subjected to a classic Thai scam called the "zig-zag".
Their lawyer urged them to expose Tony - but also warned them that if they fought the case it could take months, and they risked a long prison sentence.
After five days the money was transferred to Tony's account, and they were allowed to leave.
Mr Ingram had missed his mother's funeral, but at least they were given a court document stating that there was insufficient evidence against them, and no charge.
"It was a harrowing, stressful experience," he said.
The couple say they now want to take legal action to recover their money.
The BBC has spoken to Tony and the regional police commander, Colonel Teeradej Phanuphan.
They both say Tony was merely helping the couple with translation, and raising bail to keep them out of prison.
Tony says about half the £7,500 was for bail, while the rest were "fees" for the bail, for his work, and for a lawyer he says he consulted on their behalf.
In theory, he says, they could try to get the bail portion refunded.
Colonel Teeradej says he will investigate any possible irregularities in their treatment. But he said any arrangement between the couple and Tony was a private affair, which did not involve the police.
Letters of complaint to the papers here in Thailand make it clear that passengers are regularly detained at the airport for alleged shoplifting, and then made to pay middlemen to win their freedom.
The Danish Embassy says one of its nationals was recently subjected to a very similar scam, and earlier this month an Irish scientist managed to flee Thailand with her husband and one year-old son after being arrested at the airport and accused of stealing an eyeliner worth around £17.
Tony told the BBC that so far this year he has "helped" about 150 foreigners in trouble with the police. He says sometimes he does it for no charge.
The British Embassy has also warned passengers at Bangkok Airport to take care not to move items around in the duty free shopping area before paying for them, as this could result in arrest and imprisonment.