A girl who wore the wrong shoes to school was made to write lines 40 times saying: "Decent people take pride in their appearance."
Laura Rawsterne, 12, was sent home by Excelsior Academy in Newcastle, Tyne and Wear, along with 21 other pupils for wearing incorrect uniform.
But her mum Shirley has blasted her daughter's treatment because she says she suffers from inflammation in her feet and needs to wear black canvas pumps.
Shirley, 49, said: "I think it is absolutely diabolical. So does that mean by daughter is not decent? Children should not have to write out things like that.
"She was taken into a different room for half a hour before she was sent home. Other children were still in isolation when she left.
"The school planner says no trainers, it does not say no canvas shoes allowed. Laura has sore feet as she has had an infection in her foot for quite a long time.
"She is unable wear leather shoes as they make her feet sweat so the doctor suggested she wore canvas shoes instead.
"It took me by surprise when she was sent home, she has always worn them. I can't go out and buy her leather shoes which she can't wear."
Shirley said Laura was one of 22 pupils sent home for wearing the wrong school attire as part of a clampdown at the beginning of the school year.
Laura has been a pupil at Excelsior Academy for a year and has worn canvas shoes during her entire time at the school.
Shirley said it was only when Laura returned after the summer holidays as a Year Eight pupil when the problem arose.
Shirley, who also has a 15-year-old daughter, was told that she needs to obtain a doctor's note which proves Laura's medical condition.
Shirley, from West Denton, Newcastle, said: "Now I am going to have to pay for a doctor's letter which will cost £20 to prove Laura is not able to wear leather shoes."
She added: "I can't afford to pay that until next week. Laura is not happy. She keeps saying I am bored and I want to go to school.
"Her education is being affected. I am worried that she will fall behind at school. She loves school and wants to learn but because of this she can't go to school."
The school insist the uniform policy is clear and its actions were necessary to lay down the law ahead of the new term.
Phil Marshall, Excelsior Academy Executive Principal said: "Our uniform policy at Excelsior Academy has remained unchanged for the past seven years and we reminded parents and pupils about it before the summer holiday break and again when we returned to school last week."
He added: "The parents of pupils not wearing correct uniform were called and children sent home to return to school the same day changed into the correct uniform. Canvas shoes and trainers are not acceptable footwear.
"If any parent has a medical issue regarding their child's wearing of school uniform, the school principals or one of the welfare officers is always available to talk and help.
"Wearing uniform is important as it teaches young people that there are rules in life and also prepares them for when they go to work and the expectations of a dress code.
"We try to work with parents as much as we possibly can to ensure they understand what their children need to wear to school.
"We have high standards of dress code and we thank the overwhelming majority of parents who help us meet those."