2 ways to go High road and Low road
High Road - Make sure they don't want it back and if they insist you keep it then donate it to a raffle to benefit this site.
Low Road - Call them up and tell them you are dissatisfied and want your money back...then keep the others for free
Or you can take the Road most traveled - She said keep it so keep it, and you shouldn't feel guilty about it, because you tried