[Why would any accept a Bonus with Wagering requirements]

Hi sorry it's not a reply to this post but I'm having a problem, I had a bonus of only £1.50 and I was told that I had to wager £1155, what would be the (x) wagering requirement for that please in percentage? Hope it's ok to post on here, here is a screenshot, what do you think? It seems outrageous if they think that's right. Thanks on advance for any help.