15 pro max unlocking

hello

so recently i purchased a 15 pro max from eBay USA the old user mentioned that the phone is brand new and is unlocked upon arriving i check the phone setting and found out it was not unlocked and there is a sim restriction from T-Mobile i am very confused i contacted eBay they asked me to wait for 72 hours where i work i need to have multiple sim cards and the phone to me right now is useless i set up my iCloud the phone is perfect it s just that the phone is locked to T-Mobile .

i was asking if i should worry????  or not???? 

 the phone was not cheap and am vey worried ...