Ask for retention, or customer solutions. I work for a US cable company and it can be done via phone.

I agree with the person who said don't pay. change providers they will switch bill comes send back. call corporate cause this sounds like AT&T they can be idiots

Suddenly it seems more convenient to do this in China.

I'd go back to the store and ask them if they could help you cancel it, if they say to call ask them to be on the line with you and if they say online ask if they can show you. I'd as nice as can be but still not leave till they "help" you figure it out in front of other potential clients.

Have you considered using an carrier pigeon to try and cancel?

Complain and get angry/bitchy enough and they will help you cancel it on the phone. Like start off nice and be firm with your statement of "I want to cancel my service over the phone." Keep repeating it when they try to give you the run around. Unless you're getting verbally abusive, they can't hang up on you. Keep standing your ground and tell them you want to cancel your service over the phone. They keep telling you that you have to cancel by letter - that's when you get bitchy and be like "I've checked with your website, your store, and this is my second time calling you to try to cancel. I will not be continuing my service with you and I will be cancelling it today over the phone. If you're unable to help me this, then transfer me to your manager or someone who is more capable than you."

Or just don't pay the next bill, they'll be happy to cancel it for you.

Ahhh, sounds like my life when my husband went to "WhyNotLeaseIt" and bought me a piece of crap laptop with an improperly installed operating system for only 8 monthly payments of $120 against my will. Shortly after he signed the deal, he got shipped off to the psych ward. So here I am, paying the bills, and I have no idea how to make the lease payment. They won't let me pay it over the phone because I'm not the person whose name is on the lease. I go to the store and they tell me I have to pay by phone. We went round and round for hours while I tried to explain that my husband was NOT THERE to make the payment, but I was there with every bit of pertinent information they could possibly think to ask me, you know, to ensure I wasn't some imposter there to pay someone else's bill without their permission.... I ended up eventually having to call the psych ward and convince my mid-psychotic-break schizophrenic husband to call the company and make a lease payment while he was drugged out of his skull and barely coherent.

Stop paying the bill. They'll cancel it themselves.

I didn't realize Comcast provided services in Italy....