It usually depends on the model itself.
Check
www.liberatumovil.com , they have two shops in Madrid were you can "free" your mobile phone.
It may be another option to go to the official technical support service and explaining them the problem...
And the last option: Go to a Vodafone shop, explain the problem, and ask them to free the mobile phone (perhaps this option is the best, and probably the cheapest).
Fernando