Average cost of ending a contract is £190, Citizens Advice finds.
Internet users across the UK are being "punished" for wanting to change underperforming broadband suppliers, research has claimed.
Evidence collected by the Citizens Advice watchdog service has found that some internet service providers (ISPs) are hitting customers with massive cancellation fees for leaving, which in many cases are passed onto debt collectors.
The charity found the average cost was £190 for getting out of a broadband contract, with some customers being charged as much as £625 despite having received poor service from their existing internet provider.
In one case, a broadband user in his 70s saw his service stop working altogether after months of problems. When he changed provider he was sent a letter saying that he owed over £200 for early cancellation, which was then handed over to a debt collection agency.
Over half of problems reported to the Citizens Advice consumer service were for substandard service, with one in five (23%) concerning cancellation and withdrawal of broadband services.
Citizens Advice is calling for internet service providers to never issue cancellation fees if customers have been having persistent problems with their service, so that people aren’t being forced to stay in unsatisfactory contracts.
"People are finding themselves held captive by bad broadband services," said Gillian Guy, chief executive of Citizens Advice, which is also calling for ISPs to improve their customer service and to take more consideration before handing cancellation fees over to debt collectors.
"Internet service providers must not shackle customers seeking a better service with unreasonable fees that can turn into shock debt. All internet users need to be able to easily have a way out of inadequate contracts and broadband speeds that only give them daily frustration."