Regarding my o2 bill

Hi

This is kolla ,I have small problem with this O2 network from the starting onwords I pay more money due to some problem but still I don't know about that. Whenever I go to Saturn O2 store at oberhausen neumitte I didn't get any reply from those guys.every bad response towards the customers as we international students we don't know proper information about this. They told to me I  can talk to hotline , then I call to hotline they pick my call and talk to me in German and suddenly drop my call. This is happened from past one year , am really unhappy about your service. Atleast with this mail I hope  you guys are help me in this problem.

Thanking you

Regards

Kolla