I don't think it was particularly embarrassing or awkward. Until I read your comment, I was actually pleased that I'd been able to tell the guy that his pronunciation is a problem, because that will help him in his career. (I don't have any objection to people being employed to sell legal, ethical products and services, and I know that if a person does watch satellite TV then Sky+ is one of the better options and would save them money.) If he'd said "home telephone" then even if the phone came out as "porn", it would have been quite perfectly clear.

Also, I think there are some differences between British and North American manners, as well as differences between manners in different parts of the same country. Within my code of manners, it's not acceptable to shut the door in someone's face until you have at least attempted to reason with them. Other people draw the line in different places, and might even argue that it's beneficial to the salesman to be able to cross you off the list immediately, saving him some time. But that's not in my code of politeness.