Vodafone don't handle the locking of handsets any longer. When they did lock handsets for a brief period ~2 years ago Brightpoint handled all of this.
Somebody posted here a few weeks ago looking for an unlock code for another ~10 year old handset and it appears these codes are simply not available anywhere. These were available free from Vodafone for a couple of years from about 2001 or 2002 onwards when they stopped locking handsets.
You're far better off cutting your loses and buying a lot better phone for $20 off trademe.