Well at least you can cancel by phone. I was moving out and wanted to cancel my internet subscription last year. Months in advance, I went to their website and located (with difficulty!) their cancellation page. There was either a form online you could fill where they would call you back, or you could call them. I did the former, waited for a couple of weeks, never had an answer. So I called them, got someone who told me it would be cancelled in 3 months as requested and forgot about it. I even received a survey about how my cancellation process went.
4 months later, I received a bill for the first month after it was supposed to be cancelled. So I called support, which told me that cancellations could only be processed by registered letter, and that they had sent me a mail regarding this (which I never received). She then told me that the service would be cancelled in 2 months since it's the minimum delay, but it would be shortened to 1 month since I was moving to a place which already had a subscription with them, provided I gave the name/address/customer number of the place I was moving to. I asked if she was sure about the details and she said yes.
Now, 2 months later, of course I still received a bill. Called them again, turns out you actually need the signature of the person holding the other contract for the 1 month thing to be valid... Apparently, they sent me another mail, which again I did not receive. (I did, however, receive a late payment notice with massive fees to my new address...) I sent a letter complaining about the whole situation, and just got told to "read the contract attentively next time".
Fuck you UPC Cablecom.