Mis-sold

A term commonly used by someone who can't take responsibility for their own financial decisions, usually when they realise they don't know how to use a recently purchased product/service, or can no longer obtain a refund for said product/service.

"I have no idea how to work this toaster Jim. I can't return it because it's out of the 30 day return period."

"Don't worry about it, just say it was mis-sold and they'll have no choice but to take it back and refund".