Who shipped them? Have you checked with the company?
I ordered some canisters on eBay that were shipped UPS about a year ago. When they didn't arrive, I called UPS. For some weird reason, they said they couldn't find my address (even though they had delivered stuff to me before), so they - get this - looked up my old address where I hadn't lived for four years and delivered the canisters there. It gets better. I went over to my old address and the person living there had opened the box and my canisters were sitting out on the porch. From the look of things, she was going to plant in them.
Things happen and it sure doesn't hurt to do as much follow up as you can.
And yes, I got my canisters back. I knocked on the door a couple times and when I got no response, I simply picked them up and took them. Of course, I told the landlord what I had done before I left.