Issue with billed amounts for my contract

What exactly does your invoice say, specifically on page 2? There you can see what the costs were for. Reversing the direct debits wasn't a good idea; now you're in arrears.

I don’t have an invoice. I only signed the contract and haven’t received any bill from you. I could see the amount that was supposed to be charged on December 15th, and that date hasn’t arrived yet, so I’m not overdue.

I’m not going to pay an amount when I don’t even know what it refers to. My contract is clearly active and states a monthly payment of €19.99.

You can find the invoices in the customer portal; to do this, you should first register your phone number for Mein o2.

I already tried to register and I wasn’t able to do it. I also tried calling, and every time I finally reach someone, the call gets disconnected.

Honestly, I’m quite dissatisfied with your customer service.

That's not my customer service.

What exactly isn't working when you try to register your phone number?