Iphone Network lock

I bought iPhone 11 pro max under payment plans from Metro by Tmobile. I did all my payments and I contacted my carrier support to get it unlocked. They said it is unlocked and after resetting, it'll be ready to use. But I have already reset it three times and it is not working with different sim. I used a different sim but it didn't work. I dont use metro sim anymore. I used a third party website to check if it is locked and it states the phone is still network locked. Please help :)