Security Code?

I purchased a 2004 Ford explorer to which the battery went flat. Ford want to charge me for the security code. I do not believe they should as it was only 5 months ago.
Anyone have access to security codes?
Ford Explorer 2004
Australia
Vin No. 1FMDU73E14ZB19680
Serial No. M007795
Model No. 6006 HARD MNT GCC
Part No. 4L2T-8C815-HA

please help
With thanks
Cor.
nibroc@tpg.com.au