i transferred from EE to giffgaff farely easily. the PAC code was forthcoming (but not without a "did you know we can offer you xyz" conversation. the transfer was done within a couple of days.
unfortunately it happened on the day 02 had their mass outage so i couldnt work it if ee had messed up, or giffgaff, or if it was just one those things when transferring from one network to another. i didnt have data the whole day nor the next.
...and then i realised i had data on the mobile switched off.
so long story short, check yo'self before u wreck yo'self.