The problem is in the wording of the T & C.
Here is the corrected version.
Playthrough requirements.
As any wager could return a sizable win, players are expected to wager their bonus and deposit until such time as all of the following are met.
Deposit and bonus must be wagered 25x
To show commitment to fair play, the bonus must then be wagered till the balance is equal to the sum of the initial deposit and bonus less the amount of the bonus granted.
You are then at liberty to cancel your membership and cash out, or wager until your balance has gone, at which time you will qualify for a totally outrageous bonus offer!