Default Ugh my dumb customers!!! Please help

Hey fellas, ok so heres my deal, i have a nice Galaxy S3 i747 that i sold to a customer, i previously unlocked it by downgrading modems and doing the 197328640 trick, and everything was fine, the customer is using it on Solavei, which im sure you all kn ow is a tmobile carrier, so then she calls me and tells me the phone is saying "phone not allows mm#6" so i had her bring it back and i just gave her another S3 to get her out of my hair, so doing my damage control, i look at the phone, and she did exactly what i emphasized not to do! which was updating OTA, and now the phone is on 4.3, so as of right now ive flashed the 4.3 insecure kernel, since i cant go back otherwise ill brick the phone, and i need to RE-Unlock it, however when i try to flash an earlier baseband everytime i boot into the phone it says Basband version: Unknown, so i reflashed the MJB Modem, but i cant unlock this way.....Any ideas?
T-Mobile Galaxy Note 3
Color: White Originally, but replaced glass with Black
Root: Pff of course!
Unlocked: Yes
Current Carrier: Straight Talk using AT&T Sim (Yes LTE Works Great)
Rom: Wicked V5
Kernel: Stock
Recovery: Philz Always!