I replaced the sim card, same issue... It seems that here in NL, t-mobile acquired Orange. They didn't use their network due to incompatible devices, so the broke it down. Then the government (OPTA) forced them to start using the Orange frequencies. So they started using these on their existing sites, overloading them. The whole 3G network in crowded places is not functional anymore. It's just used to forward users to 3.5G, which isn't available everywhere. So you end up with an active 3G connection which doesn't allow any traffic going over it. Switching back to 2G is your best option in these cases, IF that's available...
So we're f*cked..

KPN has the same issue (with telfort) but less. They have an ancient backbone network though.. Which leaves us with Vodafone, which has an expensive service and monthly limits for data.
So we're f*cked...

Another option is free-WIFI like FON, which works great for many foreign cities. But we dutch people are cheap and don't want to share our bandwidth (I think it's not even allowed by the ISPs), so that won't be a workable solution either.

So we're f*cked