http://www.bbc.co.uk/news/business-16002022
Some High Street banks are charging "eye-watering" rates of interest when their customers go over their overdraft limit, research by Radio 4's Money Box programme has revealed.
A customer borrowing £100 for 28 days without the consent of Santander would repay £200, for example.
That is the equivalent annualised percentage rate, or APR, of 819,100%.