As a personal banker at Westpac in Hamilton between 2004 and late 2006, Bourton exploited her position of trust which included approving large overdrafts and loans, to open fictitious accounts where she transferred the credit to herself.
After fooling bank colleagues, Bourton then targeted new funding sources, creating a "money-go-round" in an attempt to conceal the fraud, and her offending became tantamount to "robbing Peter to pay Paul".
"She did that by targeting vulnerable customers of the bank, who she was able to extensively manipulate to her own ends, who she stole from and subsequently used them as fronts to add an air of legitimacy to her ongoing fraudulent endeavours."
Ms Foster said it was particularly disturbing that the false documents created were such that even after her departure the extent of liabilities incurred on behalf of the customers was not clear to the bank.
Bourton, who had earlier pleaded guilty to 25 of 81 charges, and was later convicted on the remaining 56, is estimated to have stolen $1.5 million and credited back $642,000 to victim James Harris and his partner Lorraine Gould.
Another victim, Jason Campbell, said he was forced into receivership and bankruptcy and then had to sell his home because of Bourton's fraud.
In a letter of apology, Bourton said there wasn't a moment of each day she didn't feel disgust, shame and remorse for what she did.
She hoped her family could forgive her for what she had done to their reputations and her own.
But Judge Philip Connell said her victims had suffered life-shattering consequences as a result of her actions, which were premeditated.
He said she had an ingrained sense of self-entitlement and a need to live a lavish and indulgent lifestyle that she could not afford.
A probation report said Bourton was extremely manipulative and minimised her behaviour, blaming it on bank colleagues, and deluding herself over the seriousness of her offending.
Judge Connell sentenced her to 7 years with a minimum non-parole period of three years.
It was a welcome relief to Mrs Gould who said she and Mr Harris had spent five years "suffering through it".
"It's her turn now and we hope she suffers as long as we have."
She said the apology was "way too late" and disingenuous.
The couple had trusted Bourton with all their financial affairs until the bank tried to sell their home at mortgagee auction, before investigators painstakingly uncovered the truth.