DSL Kündigung - Kündigungsbestätigung

Hi. I've been using O2 DSL M FLEX almost a year.
I'm going back to my Homeland, so I had to end the contract with O2.
On 20th October, I have done Kündigungsvormerkung then telephoned with telemarketer. He said I'll become Kündigungsbestätigung by E-Mail and post in two weeks. But until today, (it has been almost Five weeks) I've become no Kündigungsbestätigung from O2.

Meanwhile, I telephoned again (twice) and visited O2 Shops and wrote letters (also twice) so that I can become Kündigungsbestätigung, because next Friday I'm leaving my house in Germany.
Whenever I asked About Kündigungsbestätigung, all People from O2 were saying that everything is done without a problem. They said my DSL contract is until 30.November 2018, and it'll be deactivated afterwards. I know that, but I want Kündigungsbestätigung in document to make sure! They all said I have to just wait to get my Kündigungsbestätigung, even though I told them I've been waiting for almost Five weeks, and I'm in a Kind of urgent situation because I'm leaving Germany on 30.November. (Only a week left!)

I hope I can get Kündigungsbestätigung before I leave, but considering the fact that I didn't get any answers or letters from O2 until today, my hopes are very low.

Is there any way that I can communicate to O2 customer Service about Kündigungsbestätigung?
I'm leaving Germany in a few days, so it's not likely that I can get Kündigungsbestätigung by post. Is there any way that I can become Kündigungsbestätigung by E-Mail?