My guess is that you don't have the Next Gen seats. All three versions of the original seats heat quite well. The Next Gen do not heat the entire front half of the seat so in essence only about 1/4 of the used seat (since the back half of the part that is heated is typically not in contact with a human body) heats.To be honest I'm surprised this is even an issue. I've lived in South Dakota my whole life where the winters can get pretty awful. I've had numerous vehicles with heated seats over the years and my P85D heated seats work just as well as anything else I've owned. Is there a heat consistency problem with the seats that owners are seeing out there. Maybe I'm just lucky and mine are working fine.
The heaters in the Next Gen seats are the worst of any car I've had in about 20 years.