Blocked IMEI iphone 17

let me start by saying that I’ve learned my lesson not to buy phones from eBay Last November I bought iPhone 17 for my eBay seller when I receive the phone and look new I continue to use it until a week ago where the service suddenly stopped. I contacted T-Mobile who said the original owner ** * **owe $550 * and that IMEI number is blocked and I can’t use it anymore. I have contacted eBay for help however they’re asking me to provide a report from chechmend.com but that report is all clean despite imei showing blocked when you check it on tmobile Has anyone been able to get more help from ebay as so far they only are relying on the report from check mend.com