I just bought a Hyundai and was told by the dealer to expect a call about th service I received. Probably the best way to handle it would be just to answer once and ask that they don't call back. Most reputable companies will accept that.
Never owned a Hyundai and never will. Calls from both this number and a local Hyundai dealer of going on a year now. I blame all the traitors who buy these cars for my harassment.
As noted before, apparently calling 866-320-4607 (toll free) gets you to Synovate's (the market research company) automated system. Listen for the prompt regarding getting on their do-not-call list, then enter your phone number. According to the recording, they will stop calling your number "within a couple of days." I'll see whether that works and report back.
I, too, had my Hyundai serviced ... and to the morons who say things like "this is what dealerships do you idiots," no, harassment is not good customer service. Send me an email or snail mail, but don't call incessantly. If we don't answer after two or three times, then just quit calling. Geez.