Requesting the termination of my O2 contract

Dear customer service,

I signed a 2-year contract which began to be effective in April 2016 and my package costs 34,99(then 39.99 after 12 months) euros per month. I want to cancel this contract. The reason is that I will leave Germany and go to Italia for a Phd for a duration of 3 years. I will leave Germany on September  30th, 2016. Therefore, I would like to officially cancel my contract before 30th September. I can provide the  following documents;

(1)    Photocopy of my passport

(2)    Photocopy of the  termination of my full time work contract with my company Munich

(3)    I would be deregister from Munich on the 30 September 2016

(4)    Photocopy of a letter that I have been admitted and also registered at the University of Bologna in Italia and that I would be beginning my Phd on 1st October 2016

(5)    I can also give a copy of my Italian Study Visa when I get it in the second week of September

I will also be closing my Deutsche bank account before I leave so you might not be able to deduct  next month's premium and penalty fee from my account. I would live to settle everything before I leave since I do not want to breach the contract

My questions are;

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

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

Looking forward to hearing from you soon

Thank you so much!!

Kind Regards