On discovering its mistake, the bank took back the NZ$40,995 remaining from the original deposit.
McDonnell ignored the bank's request to pay back the amount she had spent and she was subsequently arrested.
"Any young girl on welfare like me would have done what I did," McDonnell said.
"I just went on a high. It was such a lot of money. It was in my account so as far as I was concerned, it was mine."
McDonnell said she spent the money "on everything and anything, stupid things".
McDonnell of Rathvilly Park, Finglas, pleaded guilty to 13 counts of theft of cash from Bank of Ireland on dates between 7 and 16 March 2013.
After court proceedings, the single mother was only ordered to pay back NZ$1534 and over an 18-month period.
She was also ordered to carry out 150 hours of community service.