@Roman09
Because you signed up to an offer that comes with a 7 day or month trial of boost and then its £6 unless cancelled. This is clearly stated in the offer and its T&C.
Have a full read of this to tell you all about boost.
https://help.nowtv.com/article/what-is-now-boost
Play the cancel game as I do with all my memberships, as you will be given retention discounts. Which is why I am only paying £2 a month for boost and have been for 18+ months.
FYI that I do not work for NOW, just a NOW customer trying to help
