Unlocked is not the same as unbranded. Some telecom providers lock their phones so you can only use them with their particular simcard. Mostly the case with prepaid cards and not common in every country.
If the phone gets unlocked, you can use the phone with every simcard. But due to the product code the phone is issued with, the phone is still branded to the telecom provider. And Nokia releases the firmware updates only for the phones with a generic product code. Unfortunately not for all the generic codes as I'm still waiting for the release of the Benelux generic product code.
What the telecom providers do is an entirely different story and totally their business.
So what I read from your post you have to wait till Vodafone will have the goodness to issue a new version of the firmware.
"Fatum est"