Relocating and network not updating

So I have a bit of an issue. I currently live in the twin cities metro area in Minnesota, and want to relocate to Duluth MN (a few hours north). I have Health Partners through my employer.

There are two different Networks:

Open Access Plus Network

Achieve Plus Network

The Achieve Plus Network does not list any hospitals near Duluth as in-network, whereas the Open Access Plus Network lists both hospitals in Duluth as in-network. The issue is: you can’t select which network you want; it is based on your ZIP code. For some reason, the ZIP code in Duluth doesn’t switch over to the Open Access Plus Network. I’ve called both Health Partners and my company’s HR Benefits a few times to ask if the ZIP code can be reevaluated for Duluth. When I call Health Partners, they tell me that it is decided by my company’s HR. When I call my company’s HR, they tell me it is decided by Health Partners. So my question is: does anybody know who decides which ZIP codes get which Network? Has anyone run into an issue like this before, and were you able to get the Network ZIP code to be reevaluated?