I can't use the internet

Haii all,

I have problem with my o2. Last week i was in norway, and i couldn't use my internet there. But i could make a phone call. Now i already in germany, the same thing also happen. I can call somebody, but i can't use my internet except there is any wifi nearby. Can someone help me please. I try to call the hotline, but it always said that i have to wait for a couple of minutes.