Three network offers cheap deals, and then when you realise they have no coverage, and their helpdesk is completely useless, they do everything they can to prevent you leaving. They have to provide PAC codes in a certain time frame, but they do not have to unlock the phones in any time frame, or at all.
They put lots of barriers in the way to make the process as difficult and painful as possible, they refuse to believe evidence of their own, and they give you the runaround completely.
The only time I will ever go near a 3 shop is if I see someone walking in to warn them how rubbish they are.
In retrospect I would have liked to have known that the phones were locked to the network, even on a sim only contract.