Lied to and Ripped Off

[MNIPhone12Issue]

On March 11, 2021 I clicked on an advertisement in My Verizon App to obtain a second phone by adding a new line.  I chose the Iphone 12 mini.  When I tried to complete the transaction, I received an error message that I needed to call Verizon customer service.  I called the 800 number and received a call back from Maria Angela.  She was extremely helpful and explained how my bill would be going up because I would be moving from a Shared Plan to a Start Unlimited plan.  When I asked how much my bill would be she told me $156-158/month for three phones.  I paid $107/month for 2 phones, and I would be adding a device payment for one phone, so I didn't think that sounded too bad.  She told me that the $20 fee for her services would be waived, but I might be charged a $40 activation fee.  She said I could call Verizon to have it waived.  She also told me to change my auto payment after 3/14 to be withdrawn from my checking account to receive a loyalty offer to save $40 on my bill.  She told me not to pay any attention to the "forecasted bills" from Verizon because it would all be changing.  After I picked up my two new phones, activated them, and purchased cases and new headphones, I received my first bill of $347.  For some reason, I was billed for the Start Unlimited plan beginning Feb 21st, even though my plan could not have changed prior to March 12th.  In addition, I was billed for a partial month from 3/12 to 3/20 and a full month 3/21 to 4/20.  Instead of receiving a free phone, I am now getting charged for two new devices.  Not what I was promised.  I have called at least three different times to try to get this resolved.  I was told that Maria Angela no longer works for the company and the rep insinuated that I was lying about being promised a free phone.  Another rep told me that it was the iphone 12 that had the free phone offer, not the mini, but it was too late to change.  I asked for the $40 credit for the activation fee and never received it.  I asked to speak to a manager and was told that she would pass the information along and they would get back to me.  That was a month ago.  I have been a loyal Verizon customer for 20 years and I have never been treated so badly.  What do I need to do to fix this situation?  Help!!!