Broadband customers are being hit with cancellation fees of up to £625, the Citizens Advice Bureau has warned.
The consumer charity said consumers who challenge the fees soon found themselves in the hands of debt collectors.
Other customers became locked into a broadband service which did not meet their needs or were hit by excessive fees when they tried to switch providers.
One woman was hit by a cancellation fee, even though it was not in the terms and conditions of her contract, when she tried to switch provider after her broadband speed became so bad that she was paying repeatedly to use an internet cafe.
Citizens Advice chief executive Gillian Guy called on internet service providers (ISP) to "not shackle customers" and ditch cancellation fees altogether.
More top news
The work and pensions secretary is said to be thinking of throwing his hat in the ring for leadership of the Tory party.
Prior to the EU referendum Boris Johnson spoke to ITV News National Editor, Allegra Stratton, on what a post-Brexit UK would look like.