Hang in there but return it if you can. I had a bad experience with my laptop purchase as well. (Issue wasn't discovered until after the return window.) Hopefully, you've already been escalated to their "real" customer support tier by now. I had to send mine in three times. One of those times they returned the laptop with a downgraded mainboard.
In the end I'm pretty happy with the laptop but I will never buy from them again.
Oh, they've got the laptop. They've acknowleged a fault, but the replacement part wasn't going to be available until January so they asked me to confirm whether a replacement unit would be ok, subject to availability. I said fine. I have had no communication in the two weeks since. I have no idea if they got the confirmation, whether they have stock to give me, whether they've ordered it and it's being delivered and I should expect it to arrive tomorrow, or whether they also can't get the new unit to me any sooner than January. And I can't get anyone to tell me, because the set of people I can speak to is disjoint from the set of people with visibility into the system that actually matters.
I'm left with the sinking realisation that the only option I've got left is to pursue a refund, hope that doesn't take an age to sort out, and start the whole process over again with either Dell or Lenovo. Then deal with whatever mess I get left with if I do get a delivery.
Ironically I went with HP because I'd heard Dell was having delivery issues and I wanted to avoid that hassle. More fool me.
In the end I'm pretty happy with the laptop but I will never buy from them again.