Broadband ISP Plusnet has upped its customer exit fee from £5.75 to £20 - a rise of nearly 250%.
The charge is in relation to a ‘cease' of a customer's broadband, and the increase comes into affect from 29th October 2008.
Plusnet was bought by BT in January 2007.
Carol Axe, Customer Support Director at Plusnet, explained that the massive increase is "because our supplier, BT Wholesale, has increased the cancellation charge which applies if you stop or ‘cease' your broadband service."
Examples of where the charge is payable can include moving house, or changing supplier.
Axe noted, however, that the fee does not apply if the customer migrates to another provider using a MAC key - only if he or she decides to cease their service altogether.