Terminate my o2 contract

Dear customer servie,

I signed a 2-year contract which began to be effective in May 2013 and my package costs 24,99 euros per month. I want to cancel this contract. The reason is that I will leave Germany and go to Taiwan for exchange program. I will leave Germany on July 19th, 2014. Therefore, I would like to officially cancel my contract before July 19! I now have following documents;

(1)    Photocopy of my passport

(2)    Photocopy of my Germany visa (to prove that it only lasts until end of July 2014)

(3)    Photocopy of my Taiwan visa (to prove that I will really go to Taiwan)

(4)    Photocopy of Taiwanese university’s exchange student admission letter (to prove that I will really join the exchange program)

(5)    Photocopy of airplane ticket (to prove that I will leave Germany on July 19, 2014)

I think the company also wants the leaving-the-city form from the city in Germany that I live in now. This is a problem because the city hall only allows me to process the leaving-the-city form on July 17, 2014. And another problem is I will close my Deutsche bank account on July 18, 2014. So, there's no way o2 can deduct next month's premium and penalty fee from my account. My questions are;

1. What other documents does the company need in order to let me cancel my contract?

2. After I get my leaving-the-city form on July 17, I can fax to company and can company deduct the premium for June and July as well as penalty fees from my Deutsche bank account on July 18, 2014?

3. How much do I have to pay in total?

Thank you so much!!