I am getting calls from 312 as well. They call 4 times a day. It rings once or twice and then hangs up. No message. Very annoying but at least I was able to set a contact with no ring tone on my phone so now it does not ring when they call.
We just bought an appliance from Sears today and not more than an hour later I started getting a call from "312". I've received three calls from them so far today.