support issue

I have been calling into support since October 2023 about an issue with an iPhone 15 ProMax that was stolen out of the box before it arrived at my door-FedEx delivered a torn open box. Long story short, I filed all of the necessary paperwork (police report, photo of box, etc.) the last week of October. I was told to go to the Xfinity store and purchase a new one. The trade-in deal that expired Oct 12 for $830 device credit would be honored. I did this and returned my old device - an iPhone 12 Pro Max. I received notification by email that it was received, in good condition, and the trade-in credit would be applied. It was not applied in November, or December, or January and I am not seeing it on my bill for the February billing cycle. I have lost track of how many calls I've made to Xfinity about this issue.  4-5 cases "have been resolved" but no one in support can tell me the resolution and I am not seeing it. I have been told the credit will be applied monthly. Then on January 23rd I was told since the offer is no longer an active offer that the only thing they could do is apply a $830 credit to my account and my monthly bills would be $0 until the $830 credit was exhausted. I was informed that this credit would be visible on my account within 24-48 hours. Still no credit visible, so I called on the 30th and then the 31st. On the 30th I received a text saying my case had been closed. Still no resolution. So they opened a new case on the 31st. I was told that I may have to call in monthly to get the device credit added to my account. REALLY? How about following through on the resolution promised BEFORE any of my cases are closed? And by the way, the customer support person handling my call on the 31st had me on hold for 22 minutes and finally the line went dead. I have internet, Cable TV plan, and mobile plan with Xfinity and have been a loyal customer for many, many years and this is the way I'm treated? Come on Xfinity-get your act together and follow through on a resolution!