O2 Rechnung

Hello, 

I am a customer for O2 more than a year, but still can’t understand it “Rechnung” web page.

For example what is the difference between:

-88,21 €

Letzte Rechnung vom 13.07.2020

fällig zum 20.07.2020

and 

88,21 €

Letzte Rechnung vom 13.07.2020

fällig zum 20.07.2020

When it means that I need to pay 88,21 € and when it means that there is this amount of many on the O2 account?

On my bank account I’ve never seen that O2 fetched money from my account, because of that I always transfer it manually, which looks a source of a confusion. What is the maximum period after which transferred money must be visible on the account? If there is we can make to fetch money automatically to reduce this confusion?

Edit o2_Larissa: transfered to English o2 Community: Broadband / DSL