"I was put back to an unqualified teacher. I have a beginning teacher working next to me this year and I was earning less than he was," she said.
"It was like 16 weeks all up. I was earning half of what I should be earning and I have a mortgage and three kids and that kind of thing. I couldn't tolerate it anymore."
The ministry said applications for salary assessment were reviewed within 15 working days and if more information was required the school and teacher were contacted within two days.
Betteridge said it took nine weeks before the salary assessment unit responded to her initial request and asked for more information.
She said it was impossible to directly contact the unit to explain the parts of her application they did not understand, such as which Australian schools she worked at and for how long.
"I just felt really powerless. There was no way of me being able to talk to an actual person to say 'what do I need to do to speed this up or what is going wrong here?'. You send an email and it's crickets. There's no one to communicate with," she said.
The ministry said increased applications, staff turnover and Covid related shortages caused delays between the start of March and end of June.
It said during that period correct applications were processed within a month on average.
Teacher Caleb Webb said he had waited nearly three months, even though there were no problems with his application, for a salary increase based on his routine annual step up the salary scale.
"Usually by the next pay you have your increase sorted and things go as usual.
''However, this year it's taken more than two months and I've still been waiting up until recently. On Friday I got told that they'll finally put the pay through and I'll get the correct pay next week," he said.
Webb said it had been a minor irritant, but he knew teachers who had come from overseas who had been significantly underpaid for months.
The ministry said so far this year 58 per cent of correct applications had been processed within 15 working days.
