Refund for Trade-in

I purchased a new phone IPhone 16 Pro Max on 11/11/24 and returned my old phone (IPhone 14 Pro Max).  I was supposed to receive a refund check for $430 for my trade-in.  I have spoken to 6 different agents (and been on the phone for hours with them) and they said that the promotion was not applied, and they assured me that I would receive the check for $430. A ticket was created. I was told that the promotion was applied on 12/18/24.  They have said the following: they would speak to higher management and I would receive an email with a resolution and it should be resolved within 14 days; I would be called back once the ticket was closed; the check would be mailed within 3 to 5 business days; the check would be mailed and it would be assigned to UPS or USPS within 5-7 days and I would receive an email with a tracking number; they would keep an eye on the status of the ticket and call me back, etc.  Everything I was told by each agent never occurred.  I have been given the run around so many times.  I finally received an email on 2/19/25 stating that my case had been resolved and I would receive another email with more details shortly.  I still have not received anything and this is May 2025.  I think the agents just tell people what they want to hear and never follow through.  This is pretty ridiculous.