UPDATED: Pupils at Thomas Ferens Academy were refused their GCSE results this morning – because they have not paid the balance on their iPads.
Around 20 students in the 114-strong year group were left without results for several hours.
Furious parents said staff at the school, in Hall Road, north Hull, had taken the results away and were threatening to close the doors.
The results were finally given out at lunchtime, according to pupils.
One student, Leah Sawyers, 16, said: "We got here at about 10am in the morning and it took until 12.30pm for them to give us the results. They didn't even say sorry or anything.
"At least we can relax now. We all got them in the end but it's just been ridiculous - I'm hoping that it never happens to anyone else."
Parents had been asked by the school to contribute £12 per month for the iPad tablets. Those who had not paid the balance were sent a text message yesterday, asking them to either bring back the iPad or the outstanding money.
Angela Fox, who said her daughter Leah, 16, had had her results held back, said it was cruel on children who had worked hard and were looking forward to seeing how they had done.
She said: "I'm furious. All the work they have done and the pain and the worry about results and this happens. To turn up at the school and be refused their results is disgusting."
Ms Fox said she had paid around £120 off the balance of the iPad, from a total of £288 which parents were asked to pay. She said if she handed the iPad back, she would lose the £120.
"We have struggled to pay it," she said. "There was nothing in the contract to say that they would have their results withheld. They all want to know how they have done so they know whether they are going to college or an apprenticeship."
The package, which is subsidised by the school, is worth £500.
Provisional results for Thomas Ferens Academy show that just 20 per cent of pupils gained the new GCSE gold standard.
Last year, parents reacted with anger when pupils had their iPads taken away two weeks before they sat their crucial GCSE exams, in another dispute over payments.
The school had been warned by the Government it must improve its results. However, it is difficult to compare today's results to the 2013 grades, because the Government has introduced a new, tougher gold standard this year.
The school was unavailable for comment when contacted by the Mail this morning.
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Leah Sawyers, 16, "We got here at about 10 in the morning and it took until half twelve for them to give us the results. They didn't even say sorry or anything." "At least we can relax now. "We all got them in the end but it's just been ridiculous - I'm hoping that it never happens to anyone else."