How to unlock my phone carrier (iPhone 6)?

I have Boost Mobile and when I tried to switch to T-Mobile they told me I had to talk to Boost to unlock my phone. I went to Boost Mobile and they said they don't have the power to unlock my type of phone, iPhone 6, from their carrier 'yet'. So basically they said I was stuck with them until they got a code to unlock my phone. Is there any other way to unlock my phone, since my carrier can't? What can the Apple Store do? I just want to switch carriers and they aren't letting me.

Call Apple and ask them if they are able to unlock it. OR Go to a phone store and have them unlock it.