The distraught family of an Adelaide grandmother are demanding answers after the 64-year-old died alone in a hospital corridor at the Royal Adelaide Hospital.

7NEWS has obtained damning CCTV footage showing Helen Sargent being left unattended for more than an hour with no access to an emergency buzzer, despite arriving at the hospital complaining of breathing difficulties.

When Helen arrived at the $2 billion facility late last year there were no rooms available.

Instead, she was wheeled into a nook outside a kitchen.

“She’s been treated like a piece of rubbish,” Helen’s son Damien Sargent told 7NEWS Adelaide.

The CCTV footage shows Helen’s bed being briefly attended at 9.51am on October 11.

She had a mask but no emergency buzzer to alert staff.

“With somebody who’s having breathing difficulties, you’re not going to have a blue mask over their mouth,” Damien said.

Fifty minutes later, someone walked past but does not stop.

At 10.55am, Helen is checked on and found unresponsive.

Staff immediately began CPR, but Helen was pronounced dead just 15 minutes later.

“I can’t sleep at night. All I see is mum, you know, in the corridor by herself dying. And I can’t get on with life,” Helen’s daughter Megan Sargent said.

Helen’s patient records revealed an attempt was made to move the bed into the CPR position, but it wasn’t connected to power.

There was also a delay in oxygen administration due to patient overflow.

In a tragic, ironic twist, Helen was eventually moved into a hospital room — but only after she had died.

The incident left staff so distressed they were sent home for the day.

One worker made their feelings known with a three-word statement in Helen’s medical notes: “The system stinks.”

“My mother should have lived that day, but through the hospital’s action, she’s now no longer with us,” Helen’s other son Simon Sargent said.

“I wouldn’t want that to happen to anyone, to anyone’s family.”

SA Health told 7NEWS there have been three reviews into the case, each conducted by the health network’s own senior clinicians.

The clinicians said they were satisfied the patient’s death had nothing to do with being left in a hospital corridor, adding there were no delays in providing medical support or access to appropriate equipment during resuscitation.

The coroner is yet to release its findings, but Helen’s family say they are already preparing for a legal fight.

“This great new hospital, $2 billion or whatever it cost them to build, is supposed to be one of the best in the world. Clearly it isn’t,” Simon said.