Quite simple really.
You didn't order them, therefore you don't have to pay for them. And they technically didn't deliver them to you either.
From the stuff that was delivered to you, take out what you were expecting to receive from them based on your original agreement (net of whatever were taken when in the store room), and send the rest back to the company concerned.
By sending them back, even though they'd screwed up and sent to the wrong person (whereby you could actually claim you don't know anything about what was delivered and keep everything), you're actually showing them a certain level of goodwill in order to clear up the situation and resolve everything to everyones satisfaction.