Northern New South Wales pensioners Brian and Anne Gunn have been thrown a road block in their attempt to sell their family property of 32 years.

The Gunn's adult son, Andrew, is preventing them from downsizing by refusing to vacate their land.

ln 2001, Mr Gunn built a kit home on his parent's property with their permission, and in 2006 his parents took over the mortgage on his kit home.

After fourteen years of paying for Andrew's comfortable living arrangement, they have finally asked him to leave so they can sell their block of land.

But Mr Gunn is claiming that the house he lives in is legally his and that his parents need to pay him at least $300,000 if they want him to leave.

Brian and Anne Gunn's written confirmation that they will give Andrew 25 percent of the proceeds from the sale allegedly is not enough for him, as he believes he is entitled to much more.

"He keeps changing the amount of money that he wants, and we keep telling him that we can't because we don't have any money - we have to sell first," Mrs Gunn told A Current Affair .

The bitter dispute between parents and son has turned the Gunn's property into a warzone.

The Gunns say they have had to endure shattered garden gnomes, a smashed up letterbox and booby traps.

Speaking with A Current Affair , Mrs Gunn was fighting back tears when asked to describe the torment her son has put her through.

"He's been brought up to be polite, and then this happens," Mrs Gunn said.

"I just wish this would stop. I'm sorry, I just wish it would stop," she said.

The situation also has Brian Gunn on edge, with his retirement savings tied up in the property.

"He's overstayed his welcome," Mr Gunn said.

"We just want the aggravation to stop and for him to leave, so we can sell up and get on with our lives," he said.

Mrs Gunn also pointed out that Andrew is living in the house on their property for free.

"It costs him absolutely nothing to live up there at the moment. Nothing," she said.

"We can't understand why he can't listen to reason."

CRH Law partner Brian Herd said this is a difficult case because no proper subdivision papers were ever written.

"It's just family implosion," Mr Herd said.

"You cannot have registered ownership of a home, you can only have registered ownership of the land," he said.

"As a consequence, it's a mess."