Network Extender for XM

XM uses the Verizon network.  I live in a Verizon almost-dead-zone.  I get one bar in/outside of house.  My phone does not have the wifi calling option.  Also, I have read that with wifi calling, one cannot utilize two factor authentification for banking, etc.. 

That leaves me with a very poor signal an no options to remedy the problem.

I just finished a chat with XM support.  The rep advised, after checking with "upper echelon support" that XM does not offer a Network Extender like Verizon mobile customers can receive for free if they have signal problems.   The obvious question: why does XM not offer a Network Extender?   And if XM refuses to furnish Network Extenders, why won't they allow a certified Verizon Network Extender to be registered on the XM network?  I would pay out-of-pocket for an Extender if XM would register it.

Just very poor customer service on the part of XM.