Hello!

I was planning to purchase a new cell phone and give my current SE T300 to my Dad who is still using a Nokia 5110 that is like one of Jethro Tull's albums.
Anyways, I noticed that both T-Mobile and Vodafone offer the K750i (or D750i) with a branded firmware and cover that I don't really like. Vodafone's software for example is a bit buggy as I was able to read on the Internet and D750i only supports the t-zones from T-Mobile. While I understand that the cover cannot easily be exchanged, is it possible to remove the branded firmware and replace it with the one that retail cell phones have? I saw that there are certain companies in London and other towns that can do this for you or even install the W800i firmware on a K750i / D750i, but I thought that there might be an easier and cheaper way to do this. Also, since I am not planing to crossflash my phone to a newer version, but only remove the network provider specific "features", would such an un-branding be legal?
Finally, while we're at it, even if I crossflashed my phone, would it still work with the accessories that came with it (headset, data cable) or would I need W800i parts? Can I continue using SEUS or would I need a special program for keeping the crossflashed device up-to-date? It's not that I really need the W800i since the only advantages are the music-only mode and the somewhat improved media player if I am not mistaken - I can live without them.

Regards,
Sebastian

I think such un-branding is not illegal. Even crossflashing to a newer version is not illegal. It may void the warranty, but not illegal.

As to your question:a cell-phone magazine here in my country have done exactly that and find out that all standard K750i parts work.

But you ought to check someone in your country of his/her experience, just in case.

I currently have a Samsung SGH-E720 which is quite nice (besides two very annoying points) also running branded firmware.
I asked at the shop if it could be legally removed and they are sure it's legal to do so. Samsung even offers to reset the phone to stock firmware for a fee (~20€). I'm sure this option is also available with the other big German providers.
anyway, as it is legal you could do it on your own and save a few bucks.