Trade in credit not applied after 6 months

Howdy all,

I am so frustrated with XFINITY. I purchased an iPhone 15 on the condition that I traded in my iPhone 11. XFINITY sent the trade-in credit confirmation on 1/18. I've called and chatted with many XFINITY representatives over 30 times. Each time they tell me it will be fixed, I call repeatedly. I've spent so much time explaining this situation that it's ridiculous. Each time, the representative says they added a note to my account and that it will be fixed. This last time, they even told me to call Assurant directly. I find this frustrating; why should I contact a third party to resolve a problem XFINITY refuses to solve? I don't know how to get the credit applied without calling/chatting 3-4 times each month. For example, I've already chatted three times to get the credit applied for this month. Has anyone ever dealt with this? How do I get XFINITY to fulfill their commitment? I need the credit permanently allied to my account. I've posted this before and still no help