Phone [Q] Canadian (MTS) Galaxy S4 SGH-I337M unlock

I have a Canadian model (SGH-I337M) Samsung Galaxy S4. I've purchased a new Google Nexus 5 that will be arriving tomorrow, and I am planning to sell my S4 to recoup some costs.

FWIW: I am staying with the same carrier so as not to void my contract. I will simply pop their SIM in the new unlocked Nexus 5.

Canadian law states that after 90 days (it has been almost a year), the carrier must provide an unlock code. However, my carrier wants $50 to do this...this would sharply cut into the profit I could get selling the phone.

I've tried 3 online sites now, and all have gotten back to me within a few days stating they are unable to provide a code for my phone (not in database or something)

I've tried a number of the methods I've seen on xda-developers, they have all failed at at least some way through the steps where it simply does not behave as expected, ie the menu to actually change things just doesn't appear or the phone just spontaneously reboots back into normal mode.


Specs:
Model: SGH-I337M
Android version: 4.4.2
Baseband: I337MVLUFNE1
Kernel: 3.4.0-1529758
Build: KOT49H.I337MVLUFNE1
Secure boot status: Samsung
Security Software version: MDF v1.0 Release 2


I'd prefer a way to do this without rooting the phone, but am open to that if it's the only way.

Thanks!