I have reasons to believe that Bwin is intentionaly or at least roughly negligent screwing its casino players when playing with a bonus.
A quick summery is that you have to do more wagering than stated in the bonus terms and that exhausted boni will not get removed, adding additional restrictions to the players gambling.
Furthermore the terms are also really intransparent and bwin hides improtant terms in gerneral terms and bonus terms.
For more details please watch the following video:
https://youtu.be/JlJAnOS0TpY