Incorrect billing

Dear Sir / Madam,

I have concluded two contracts with O2, for two handy numbers - one for me, another for my friend. Tarif O2 Free M Boost mit 20 GB. 
As a present O2 employees gave us two free sim cards for 3 GB. They said these two sim cards are totally free.  

I was surprised when I see that O2 took money for sim cards activation 4 times, instead of 2. 
How I was trying to reach your company:
1.    In November I came to your office near Alexander Platz to explain the problem, but they said in rude form that they can’t help me. 
2.    Secondly, at 07.11 I came to the office there I took the sim cards - Schloßstraße 34, 12163 Berlin. The employee said that it is a technical mistake, he will fix it and O2 will return my money in a week. He promised to call me back at 08.11. But he didn’t call back and I didn't get money. 
3.    After that I send an email to the employee who make us sim cards - Steve N. (xxxxxxx). But he didn’t answer.

I please you to fix the situation asap and return money that was taken from my account by mistake. 
I am already going mad about the situation and ready to take legal action.

Waiting for your response by email.

Best,
Svetlana

Edit: Email Adresse entfernt / o2_Flo