I've recently purchased an i8910 off eBay.
Getting it unlocked was a nightmare, a half hour job took 5 1/2 hours via a local so-called repair centre in a dodgy area of Nottingham.
Debranding was an extreme opposite-I tried Blast Communications in Mansfied Woodhouse (after finally getting through to Samsung who recommended them..!) who weren't cheap at £20 but had a decent tidy premesis, took plastic issued a receipt,phoned back when the work was completed,offered a guarantee and had a friendly and professional attitude.


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It is shocking but the above factors are absent in all the other outlets of this type in Nottingham

So if you've got any unlocking/debranding issues you could do worse than give them a try.
On another note a debrand is definitly worth doing, my handset benefitted by being about 20% faster in operation , having the complete Samsung apps reinstated and an apparent increase in battery life.