Huong Phan said when she sold her house in Towns Crescent, Turner, to the government for $655,000, she had filled out the form asking for the first right of refusal.

But she had now been told she could not buy the block back as of right, and must compete on the open market when it is sold.

The house is a dual occupancy, and Mrs Phan also owns the house behind, which was not contaminated with Mr Fluffy asbestos and is not party of the buyback.

Under the mass demolition of more than 1000 asbestos-contaminated homes, Fluffy owners are given the right to buy back their cleared blocks, at a price set by the government, before the blocks are sold on the open market.

But a spokesman for the Asbestos Taskforce said the first right of refusal did not apply to homes on dual occupancy and other unit-titled blocks because the process was more complicated, involving negotiations with the other owners on the block, and because it took longer. The decision had been made by the government in 2014 and clearly communicated to owners.

"This decision reflects the practical and legal difficulties in acquiring and demolishing unit-titled properties, the need to involve owners of other units on the relevant units plan in decision making processes, and the resultant uncertainty in relation to when unit-titled blocks might be available for repurchase and rebuilding," he said.

"In effect, the government decided to assume these time and financial risks and uncertainties – including through longer holding times on acquired unit titled properties."

Real-estate agent David Whittem managed Mrs Phan's two homes, which were both rented, and said at the time of the buyback he had encouraged her not to sell. But given the home could not be rented and she had to pay the mortgage, she felt she had no choice, he said.

"It's unbelievable when she owned the property, when she owned both of them, to tell her she can't buy it back," Mr Whittem said. "I can understand if it was a multi-unit site, but it's only a dual occupancy."

Given she still owned the back house, the front house was worth more to her than to other buyers, making the government's stance even more difficult to understand, he said.

Separately, O'Connor Fluffy owners Mary Hutchison and Maureen Cummuskey have been offered their Fluffy block back at 10 Quinn Street for $800,000, after the government paid them $820,000 for the house and land together.

Ms Hutchison said it put the block well out of their reach, and the pair have since moved from the heritage Tocumwal house they loved and renovated, and have started again in Hackett.

They are not alone. In Ainslie, Christina Pilkington was asked to pay $725,000 for her land, after being paid $735,000 for house and land combined.

By November last year, 36 owners had been asked to pay more to get their land back than they were were paid.

Ms Hutchison wants a board of inquiry to look into the history of Fluffy asbestos and the buyback and demolition.

She doesn't criticise the ACT government for its handling of the scheme, and says the government has simply been able to take advantage of the dramatic change in the property market since October 2014 when the buyback prices were set.

But she worries that the scheme has caused hardship and heartache for many owners, and said she feels regret and sadness about her own home.

The unimproved value of her 843 square metre block in 2014 was $565,000, and she had expected a price somewhat higher but not massively higher. The unimproved value of an equivalent neighbouring block now was $611,000.

"I don't feel comfortable saying this was unfair. Something had to be done and some things didn't work out very well," she said.

"The original intention seemed to have a lot of possibilities and capacity for flexibility, that's what it seemed to be at first, and it seemed quite sensible. I felt okay about going into the process to begin with - and then it got tougher."