What is service, anyway? The verb is to serve. Are you getting what you came for? If yes, you're a satisfied customer. You may buy again.
Customers who get less are dissatisfied customers. Their response depends on the degree of dissatisfaction, from giving it another chance to outright dissing the product. I think we can give poor odds on the customer buying again.
Getting more than what you came for creates apostles for the brand. People like to share the word about good deals so long as it's a plentiful resource--you wouldn't share the location of your treasured powder stash with a stranger on the chair like you would share the name of a new carpet cleaning product that truly does get pet vomit out of carpets to all your cohorts at the doggy discipline class. This group will buy again, barring circumstances beyond your control, and bring along friends and family.
Creating apostles unleashes the power of compounding interest--arguably the greatest force in the universe.
Customers decide how the service was and whether they'll buy again. The problem is, most organizations don't go out and get the vote: they don't know that they're in trouble with their customers soon enough to effectively reverse the tide.