Sorry if I appear a bit dense but I was about to make a claim of £535 in charges without any interest charges added on to that. In spite of reading this I am still unsure of how to calculate the interest charges made. On my statement above each charge, ie unauthorised overdraft fee £20, there is an amount of interest charged. Do I take this whole amount or if not, what proportion of it should I calculate? In one case I am overdrawn, there is a £20 unauthorised overdraft fee and interest of £16.58. I dont like to be a nuisance but interest always confuses me.