BB is not a true debit card so you cant get MOs with it.
Post offices are being blocked by card issuers for cash like transactions.

Use your GC at WM to get a GC.
You can swipe up to 4 GCs per transaction.
If your cashier is skittish I would so for one 1k MO (two $500 GCs) and come back as many times as you need to.

Good Luck