Contract cancellation

Hi,
I did a contract in July asking to port my existing number to o2 from my current provider.
The transfer of my number was rejected and without knowing I ended up with 2 new numbers( one for me and one for my girlfriend).
I was never informed from o2's salesman that I will get new numbers but only that he will do the port of the number and the contract will start as soon as my number will be part of o2.
So since July I'm paying for 2 numbers I never used. In addition, the contract I signed doesn't even mention the existence of a new number.
Following o2's salesmen instructions of how to cancel this as they considered my case as fraud, I deducted back from SEPA the amount of the activation fee which they told me would be for free.
I ended up with a deactivated contract and with the possibility to pay the entire amount of it for 2 years.
I am constantly try to get in touch with the headquarters in Nürnberg for the last five months by sending 3 times my request but they completely ignored me.
Could you please tell me what are my options?
If you need further information regarding my case, I will be more than glad to provide to you.

Thanks in advance.