I'm confused about my bet365 new customer offer. I deposited £100 to get a £100 bonus. The bonus is not useable until I've wagered my £100, so I did so. For that particular bet, my back bet won so there is £240 cash in my bet365 account as well as a £100 bonus. I wanted to withdraw the cash and play with my £100 bonus only but withdrawing it cancels out the bonus. I also have to settle a total of £600 to make the bonus withdrawable. On a betting slip, I don't have the choice to use my bonus - there's no tick or drop down box for it.
What am I doing wrong?