How to get 4 digit personal identification number for contract termination?

I already did that without any success. This contract was forced onto me in the first place. I’m paying for a year now for something that I dont use. I write 4-5 letters without any kind of response. Tried their customer support on whatsapp tried to write into the forums. Nothing is working I’m scared at this point that I’ll have to pay for this forever. Now I figured there is an online way I wa excited at first but then this 4 digit pin thing came along. Now I’ve to acquire this somehow to cancel it by phone. I feel like I’m being scammed and so close to go to a lawyer about it. I know contracts are complex in Germany but it shouldn’t be impossible.

Hey Tobias, thanks so much for ordering my 4-digit ID so that I can terminate. I have 2 contracts at the moment to O2 that’s why I was so unhappy. While I was moving I wanted to get a 1-month unlimited internet, but lack of German skills combined with my carelessness in the process, so I ended up having a super expensive second contract like a year ago. Since then, I’m trying to get rid of this contract without any success. So I already paid 40 euro a month for a year now and after the termination it looks like I’m going to keep paying at least another year which I never even activated this number because this wasn’t what I was trying to do in the first place. But it’s just so hard to get any help from O2 you are the first person that is actually helping me in English so far. So I appreciate that but people that doesn’t speak the language really shouldn’t treated this way I’m working hard to earn my money and this just bothers me so much, and I can only imagine how many people going through something like this and can’t even react because bureaucracy and the language. But again thanks so much for sending the ID.

Is there a format for cancellation via letter? I cannot find my Customer PIN even.

Thanks