Just call and cancel. I highly doubt they will impose a penalty as their billing system prorates when you cancel out a premium special. When asked why you want to cancel just say you're not watching it and leave it at that. Don't even bring up the whole Torchwood story and the previous csr. It's tmi and will only result in making the process longer and more likely they will want to penalize you for accusing someone of lying when it might've just been a simple mistake as to when the show was coming back.