Phone bought best buy “unlocked” but not. Neither t mobile and best buy helped. I have all the receipts. I am in other countries and no phone because of that. Really need help! I have all documents proving that I bought the iphone .. please

Only Apple sells unlocked phones, the ones sold for any carrier at Best Buy (and they label it that way) lock to the first carrier they are used with (apparently he used it with T-Mobile). Only T-Mobile in that case can start the unlocking process and if they refuse to do so there is nothing else that can be done. Apple cannot help with this.

Best Buy does NOT sell unlocked iPhones. ONLY Apple can sell you an unlocked phone. You will need to work this out with Best Buy as neither Apple nor anyone here can help you.

This is a classic example of why it is always best to buy an iPhone in the country you live and will use it. iPhone warranty is not international either. Should anything go wrong with a phone purchased in the US requiring warranty support will need to be physically brought back to the US.