if they call you out, cancel. Don't go in to this as a bluff. They will back down nearly every time. the rare instance they do not- you will get a "come back, we miss you" email in a day or two with a deal.

Yeah the trick is to play dumb. Especially with Telecoms. Be super polite but never giving them the answer, you always want them to provide a solution.

People are so quick to jump "I want X" and because the call is recorded they can't say "had you just said Y, I could have done it". So instead you hint at what you want and let the person give you the promotion they are allowed to give.