Why do places not return calls?

We bought this O'Charley's Honey Mustard dressing, made by a place called Donelson Foods, and it turned out we still had another bottle (we get them in 2-packs at Sam's Club), so it was sitting around for a while, but the expiration is not until October and the stuff we just finished was good until June according to the label, and it was still fine. So, it looked really dark and separated, the new stuff, and I shook it up and I poured some out, and it was really runny and looked nasty. I keep forgetting to take the bottle to work with me to call, so I called one evening, and they were closed, but they said I could leave a message, so I did. No one called me back and I'm really irritated about that.