The GP reviewed the woman the following day and she was admitted to hospital, where she died days later.
Deputy Health and Disability Commissioner Rose Wall said the rest home failed to provide services to the woman with reasonable care and skill.
She recommended that the rest home arrange for further staff training regarding pain management and apologise to the family.
General manager of aged care for the Oceania Care Company Ltd, Barbara Sangster, said the incident happened more than two years ago and since then the company had implemented a number of changes.
"We improved all of our systems and these have been approved by the commissioner with evidence."
They received a four year certification period from the Minister of Health, which she said was a good result for aged care.
"We have also since won awards for people's choice and we have had no complaints from any residents."
"We are obviously deeply regretful for what happened and we have apologised to the family."