A contract termination

Hello, O2! I would like to terminate my contract, but have no idea how to do this without sending the paper mail or fax. I tried to terminate the contract about 4 times but I can get all legal technicalities and my cancelations were canceled. Please help.

Currently I’m a client of O2 in CR can I fill the papers for the cancellation in some Brno’s O2 office to be sended into a german branch?