Request for bootloader unlocked

I have purchased phone from AT&T and it was bootloader locked. Since I am not in contract with AT&T anymore and have paid all the fees they need to free up my device. I am asking a written document from AT&T saying that Samsung should unlock my bootloader. Otherwise I am planning to go to consumer complains. 

AT&T's unlock policies only include carrier locks. Carrier locks include SIM and Network locks. Bootloaders are completely different. Since they allow for the modification of operating systems, carrier branded devices will have them locked. Carrier branded devices are intended for general consumer use, and most consumers don't even have a clue what a bootloader is, much less a use for an unlocked bootloader. It becomes easier to brick your device, and the warranty would be voided, as such it's best practice to keep the bootloader locked.

Samsung's Response: "We would like to inform you that the devices released through carriers are bootloader locked version’s. However, devices with unlocked bootloader’s are available through Verizon and AT&T. Hence, we request you to check with the carriers for further information regarding the query."

The devices which they speak of are Nexus, Google Edition, and Developer devices. Carrier branded devices will have locked bootloaders, regardless of carrier. The only way to unlock the bootloader is to push an over-the air update that will allow the bootloader to be unlocked, followed by an opt-in process to unlock the bootloader (that will in turn also void any warranties.) Since the amount of users that want an unlocked bootloader isn't justifiable to push an update that'd unlock it, AT&T will not take action to allow the unlock of a bootloader. It's not as simple as putting in a code, such as is the case with network unlocks.

It would be fine to AT&T give me written document saying that "AT&T will not unlock bootloader even if customer is out of contract". That would help me in my process of unlocking of my bootloader in "proper way". 

[Edited to comply with Guidelines]

The Bootloaders are locked by the manufacturer.  Yes, ATT asks for it.

You can go buy an unbranded phone and it's bootloader will still be locked if the manufacturer chooses to do so.  

Non carrier phones are easier to root.

Carrier phones are often encrypted as well as boot locked

The manufacturer looks at the product as a whole as theirs, hardware and software.  They don't want it altered.

If you don't want a locked phone, buy unlocked, un branded phones.  

I purchased the blue topaz GS6 off eBay, new and un fettered, for $510.