If that vendor ends up being a “no,” it’s extremely helpful to them if you tell them as much. You don’t have to go into detail; simply saying something like “Hi. Thanks for your time. We’ve gone in a different direction.” works wonders.
Your wedding is YOUR WEDDING. It’s the main focus of your time, energy, and money. Wedding vendors know and respect that. They also have between one to five dozen more clients just like you who they are also trying to serve.
Does this vendor require a meal? How many hours did you hire them for? Is tip already included? When is your next payment due and how do you pay it? Nearly always, you already have the answer. Check the contract.