Hi,
Apologies for writing this in English, my German is still a work-in-progress.

Explaining the weird situation of routers:-
I applied for a  Telekom - Magenta Zuhause L connection for my new apartment. I realized that when Telekom sends the Speedport router I would not be there to receive it (since we had not shifted to the new apartment yet). I went to Telekom Kundencenter and explained them this. They gave me a 2nd new router saying that the 1st one will automatically return when no one receives it.
When we shifted, the connection was installed with the 2nd new router. Two days later my new neighbor gave me the 1st router, since he had received it on my behalf. I went to the Telekom Kundencenter again and returned the router (and got a receipt/confirmation).

It has been more than 40 days since I returned the router but I am still being charged for it ( invoice mentions the rent for two routers instead of one). I have got two invoices since then and both have charged me 5 Euros + taxes extra. I have complained via Telekom-hilft page on facebook, also spoke to a "team-lead" customer agent on phone. Both assured me that the first router which I returned would be cancelled and my next invoice will automatically be adjusted. But apparently they are not being able to locate the returned router and cancel the rental contract retrospectively.

I am really frustrated since no one is giving me a timeline to resolve this. It really should not take this long to resolve a simple issue like this one. This is not my fault since I already have the confirmation (attached the photo) that I returned it. Can anyone guide me on how to escalate it to Telekom headquarters?