World Class Service is Poo

T-Mobile has this World Class Service option where you are supposedly able to turn it on when in the US, then pop over to Europe and be able to use your phone without a problem. Sounds great, but the catch is that it does not world at all.
I have tried to work it out in Graz, Austria at a T-Mobile store with no luck. Then down in Ljubljana with no luck. It is driving me nuts because these are major cities. It is not like I am trying to get it to work in Podunkija, Kazahkstan or anything. I tried to change my SIM card number to an international one with no luck. I tried to manually set the network with no luck. I have tried a million things and it just refuses to work.
Such crap and really, if I (an IT professional) can not get it work, then who can really? Such a steaming, flaming bag of poo. Luckily, I bought a new SIM card in Austria and that has been serving me pretty well for SMS and what not.