Schools buying laptops and other IT equipment are being forced to pay as much as 10 times their recommended retail price as a result of mis-sold or unfair lease agreements, according to a BBC Radio 5 live investigation.
According to the BBC, an industry insider says the overcharges could be worth hundreds of millions of pounds.
In some instances, finance companies are chasing head teachers for payment for equipment that they were told was free.
The BBC investigation identifies Glemsford Community Primary School in Suffolk as one of the schools now being chased for money.
The school was offered free hardware including laptops by services firm Direct Technology Solutions (DTS). DTS had visited the school saying it wanted it to become a "flagship" for its services. When the school signed for the kit it was assured by DTS that there would be no charge as it was all part of its efforts to promote the firm.
According to the BBC, however, the school had unwittingly signed long-term lease agreements on the equipment, and when DTS subsequently went into administration, the school was left accountable for the cost of the kit, now owed to the bank.
The school leased equipment with a value of about £700,000 and now owes an estimated £500,000 to Clydesdale Bank.
The BBC believes many other schools have signed similar lease agreements for IT equipment without investigating the company they are leasing from.