When the National Trust for Scotland made a global call six years ago for families to live on the beautiful, car-free Hebridean isle of Canna, for many it seemed a dream opportunity.

For the island, left to the Trust by folklorist John Lorne Campbell, and then only home to 15 inhabitants, it was a chance for repopulation and rejuvenation.

But the dream is over. The last family on Canna has just packed up and left – only singletons remain and the population now stands at just 10, the lowest ever recorded.

Alison and Duncan Spence and their two children are part of the "Canna 16", as they call themselves – families who have quit the island in the last nine months, all blaming poor management by the National Trust for Scotland (NTS). The dream has ended in hurt and anger.

The 16 have complained about the Trust's unwillingness to enable them to set up businesses or let them own their own home, and there were difficulties over even obtaining a piece of land to garden.

Alison Spence accused the NTS of "dragging families [to Canna] and wrecking them".

Sheila Gunn, who ran the bed and breakfast on the island, broke down in tears when talking about her experience. She and her husband have called for an inquiry to be held into the management of the island.

Neil Baker, who for two years was the gardener on the island, said: "It's clear from the fact that the NTS is failing on one of its stated aims – to increase the population – that they're managing it badly.

"They've spent vast amounts of public money on Canna, but they've failed. People have been coming and they haven't been staying. That's because the NTS policies aren't in place to enable them to stay. I don't think they want people to stay."

The NTS's response to the departures is regret. In a statement on the Spence family's leaving, it added: "We are now reviewing these procedures to ensure that prospective residents have a full and realistic picture of island life before they decide to make the move."

Alexander Bennett, NTS regional manager, said changes were already being made, particularly in the area of tenure of housing, adding: "We're also planning to spend more time with the new families on the island prior to settling and make them more aware of the pressures they'll be facing. It's not a picnic out there. But some do survive. We've got survivors who are happy."

One such survivor is Amanda Lastdrager, who runs the island's restaurant. She said she has learned not to try to change things, but to "let the island come to you".

She said: "The people who stay seem to be able to adapt to the hardships of life here.

"There has been a lot of criticism of the NTS and no doubts some of it is warranted, but I think that is sometimes an easier option than perhaps facing your own issues. They, as landlords, do make mistakes, but if you have ever lived in rented accommodation that is not unique to them."

For the Spences, the last few weeks have been a blur of packing and unpacking. Having fled the island, they are now living off savings, and have moved into a borrowed house in Laggan in the central Highlands while they try to find work.

Alison Spence kept a blog about their time on the island which details the family's mounting frustrations. In one entry, she wrote: "We feel like we've had the stuffing knocked out of us; we feel like we were not wanted on the island by the NTS; we feel like obstacles were put in our way - we feel badly treated; we feel used."

Among their concerns were the low temperatures in their home, the Trust's ordering of them to take down a satellite dish, disputes over jobs promised to her husband on the island – which, the Trust says, he did not produce qualifications for.

Problems even arose before they arrived on the island, when the Trust was unable to let them move into the house they had been promised because it was not ready, but offered instead a temporary home.

Spence now questions whether the Trust is really interested in community at all. She said: "Perhaps community is a thorn in the side for the NTS. They do castles and paintings very well."

Nevertheless, the Trust continues to say that community growth is one of its aims.

However, Bennett said he is "not sure it was exactly what the Spences expected when they got there. It's not everybody's cup of tea."

He said many people who apply to live on the islands have "romantic notions" and added: "It's not easy living cheek by jowl with other people."

He emphasised the effort the Trust makes when selecting people, and said: "We don't go into every bit of minutiae about their past life to find out what they're running away from, but it's a pretty rigorous process. And with the Spences we thought we had thoroughly explained what they were getting involved in."

The Canna 16, however, are indignant and view such comments as hurtful and inaccurate. Baker said: "It wasn't living on an island that was the problem, it was that you couldn't move forwards. We came up with a couple of business ideas and the Trust just dragged their heels."

For Geoff Soe-Paing, the main problem was they were unable to buy property or put down more permanent roots. However, the NTS is not able to sell land.

The 16 have now scattered. Sheila Gunn and John Clare moved to Eigg, where they run another bed and breakfast. The Bakers now live on Islay. Geoff and Eilidh Soe-Paing moved to Fort William, though still pine for an island. All profess still to love island life. Given this, why have so many left?

Baker said: "Look around at the other islands. Many are doing much better. Many are growing. Canna has had huge advantages financially, it's had wealthy people around the world donating money to it. But Canna is the one that's failing. Questions surely have to be asked."