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I do get the text each month telling me when the bill is ready but I must admit that I didn't bother going on-line to check the amount because there hadn't been any problems before. So now I have started checking regularly, at least once a week.
However, because such usage by a 3rd-party is not blocked by default and I did not receive any notification that somebody wanted to set it up, there is no way I could have known about this charge until after it had happened the first time and the account had been debited. Maybe I was fortunate that it was only £1.25 a week and not a lot more, but losing any money through what I consider to be unauthorised actions by a company doesn't feel lucky.