I cancelled at the start of last year and did it on chat - I told them I was emigrating to Australia the following month and it still took over an hour to cancel. They have scripted responses and can't deviate from them - I'm leaving the country "Which channels do you like to watch", I won't be here to watch them "We can surely work out a package for you". Just cancel it will you "But will your family miss the movies"
It was a joke, I think my last line on the chat was "I have repeatedly asked you to cancel my subscription, I have a copy of this chat, I will cancel my direct debit, good bye"
I only found out the cancel by chat option through google as it is not clear or easy to find on their site.