Britbox is taking money from my account although I cannot access it.
I have done the reset password link and then tried to sign in, it lets me sign in on tablet but not on roku. I do not want this as not working
Without signing in it will not let me cancel and britbox themselves won't help at all as they are directing me back to Roku, just going round in circles! Option to cancel when signed in on tablet keeps saying to cancel through roku
There's two ways to access Britbox on a Roku device - through "The Roku Channel" or through the stand-alone Britbox channel/app. Have you tried accessing it both ways? Does the subscription show up on your account at https://my.roku.com ? If so, you should be able to cancel it there.
There also appears to be a UK and US version of the channel/app, so it may help to know where you're located.