Locked mobile even though fully paid for it by T-Mobile

Hey T-Mobile community! 📱 I recently purchased an iPhone 12 Pro from Target, thinking it was unlocked. Turns out, it's locked by T-Mobile even though I fully paid for it. Target suggested reaching out to T-Mobile, but after a live chat, it seems they can't assist. 

I'm puzzled because my friend had a similar issue with AT&T, and they unlocked his phone swiftly through a simple online request. Can't T-Mobile check the payment status and unlock it using the IMEI? I'd appreciate any guidance or support on this matter. Let's make sure everyone can fully enjoy their phones hassle-free! 🤝 #UnlockMyiPhone #TMobileHelp