Confirmation of DSL contract termination

Hello!

I've been a happy O2 DSL customer in the last 2 years, but as I became an employee of a competitor, I got a better DSL+TV offer...

I have done the cancellation notice in Mein o2 app on 26th of July and I called the provided phone number on 29th of July 2019.
The O2 colleague confirmed that he registered my cancellation for the end of August, as I had a DSL S Flex contract. He said that if I change my mind, I can call back and he can make me a better offer; if not, my contract will be canceled by the end of August 2019.

As I didn't call back, I would expect that my contract has been already canceled, but to make sure that everything is fine, today I've tried to get the confirmation from the same phone number.
Unfortunately I had a bad experience with your service: the first o2 employee hang up without saying anything when I tried to switch to English (as my German is very bad) and then the next lady told me in German that her colleague has already answered me and hang up also directly...

So could you please confirm if my contract has been canceled at the end of August?

Thank you,
Felix