Unlocked phone still not accepting new sim

I went through the unlock process and received approval.  The status shows approved.  I've attempted to put in 3 different sim cards (non ATT, we now live internationally).  I know this company Tigo is supported because I have two other iphones that were originally ATT that are working fine, including with the new sim I have.

Anyway,  I've tried resetting the iphone to factory settings.  I've tried connecting it to itunes to restore from there, I've tried all options I have been able to find here on the forums but I'm still receiving a SIM not supported error.

One forum post stated that after they opened a ticket, someone was able to resolve the issue because for some reason the phone was still attached to ATT even though it was showing unlocked.  I cannot figure out how to open a ticket.

I tried chatting but you have to have an ATT account to get past the automation and I don't have one.

So if you could direct me on how to open a ticket or other things i might be able to try to get this phone working on a new SIM card that would be great.