“Oh nice, who've you got taking care of it? And how long have they been looking after you?”
Why it works: Never argue with 'we already have someone.' Ask about it instead. You learn who the incumbent is, and asking about their experience makes them do the talking, which is where the cracks show up on their own.
“That's great. Honest question, when's the last time they actually came out and checked, or followed up with you? A lot of folks I talk to signed up years ago and haven't heard from them since.”
Why it works: You don't win by bad-mouthing the other company, that makes you look desperate and them look foolish for choosing it. You win by helping them notice what isn't working. Let the gap speak for itself.
“Perfect, then you don't need me to sell you anything. But since I'm already standing here, want a free second set of eyes so you at least know you're getting a fair deal? Costs you nothing and takes three minutes.”
Why it works: You lower the commitment to almost zero and reposition yourself as a favor, not a pitch. A free look now beats leaving a card every time, because a happy-enough customer never calls the card.
“I love that you're loyal, honestly, that tells me you're the kind of person who values doing right by people. All I'd ask is that whoever you're with is actually earning it. Can I show you what that should look like?”
Why it works: Loyalty is the real emotion behind 'we already have someone.' Attack it and you lose. Honor it, then gently raise the bar, 'are they earning that loyalty?', and you turn their best trait into your opening.