Rose Ashton-Weir was identified as a gifted student but began losing interest and started failing math in year nine at the Geelong Grammar School.
"I never developed the skills and they never instigated a system to help me rebuild those skills," Rose said.
Her mother Elizabeth Weir claims her attitude and her results improved quickly after she left the $45,000 a year boarding school to attend a Sydney TAFE College with $500 a year fees.More stories from Today Tonight
"I had concerns about what happened at the school and I tried to communicate with the school about those concerns, and I found there wasn't an available complaints system," Elizabeth said.
"Honestly we're shocked that for $500 a semester you get better education than you get for $45,000 a year."
They are seeking compensation for school fees and relocation costs. The school argues it was not the tuition or support that was lacking but Rose's effort.
A hearing continues before the Victorian Civil and Administrative Tribunal.
This reporter is on Twitter at @MattWhite_7