Landline vs. VoIP and billing

When I moved into this house almost 4 years ago, I was apparently misled that I had a true landline (copper POTS) and saw pole lines going into the new interface box.  Apparently not, and have been paying monthly for a voice service, expecting to have an emergency landline during power outages. Who do I connect with to complain and see about some sort of compensation as a Platinum Loyalty customer?