Not honoring promotion

I purchased two Iphone 13's on November 28, 2022, under the Black Friday Holiday promotion. These lines were both considered upgrades and not under contract.  The website said $5 a month after credits with no trade in required.  I have an unlimited line and meet all of the other requirements.  I paid the upgrade fees and for 10 months now have been billed the full $20 rather than $5 per line each month.   I have spent numerous hours on the phone and eventually they find the promotion and tell me I will be credited back what I paid, and the forward billing will be corrected. Then it stops there, rinse and repeat. The tickets get closed, and the billing never gets corrected.  I'm now going on 2 hours for my 4th call, and she is telling me she can't find that previous promotion and essentially my previous cases and text confirmations are useless. Is there no other option prior to seeking arbitration or legal action?


Best Black Friday iPhone deals 2022 | Tom's Guide (tomsguide.com)
New Black Friday Apple iPhone deal at A&T: Get an iPhone 13 for $5 per month | MacPrices.net