do you have deposit bank equal with debited in USD as in picture?ussually debited is converted to local monetary as in your example CAD .
http://i63.tinypic.com/xqkx1z.jpg
if not go to chat support and tell them to change that , thats the only problem that charge that fee. if you still have in usd , somewhere else is the problem ( of course if you have selected usd when cash out.
if you dont have that 888poker charge 3 times conversion
1. usd-debited currency ( saying in this case CAD)
2.cad-usd ( becouse you have selected usd when cash out was made and not cad )
3.bank will make the conversion if you have other currency than the method you have cash out
hope that helps. so the only problem is debited currency wich should be usd same as play currency