My employer signed me up for the wrong insurance plan, and I’m due to have a baby next week

I’m a little stressed right now because my employer sponsored health insurance changed on the first of the year. They changed insurance companies and we signed up in November for a specific plan. I picked that plan because I’m due to have a baby anytime now and the out-of-pocket max was low. Well today I activated my insurance account and the details for my new plan were all wrong. They signed me up for the very high deductible plan offered through my work for free. But I double checked my election on my employee portal and I did sign up for the correct low out-of-pocket that I wanted. Which means my employer will be payroll deducting my premium based on the plan I wanted, not the freebie plan they actually signed me up for.

How do I fix this before I get hit with a huge hospital bill for labor and delivery?? Should I start with my HR representative, the insurance company, or both? If I end up with that high deductible bill should I ask my company to reimburse me? Thanks for any help anyone can provide.