Fedex Duties

I bought a new CPU off Ebay and it was sent from Poland (I'm in the UK). The item itself cost around £160, plus a £16.66 shipping fee. I assumed this shipping fee would include any customs duties that would need to be paid, but I have received messages and mailed a bill from fedex asking for a total of around £44. Do I need to pay this? If I do does it seem a bit high and may be able to get it reduced?