My Internet stopped working one month before termination period, why god why?

A month ago I sent a termination letter confirming that I want to cancel my contract in the 31/10/16 or the first optional date after. Yesterday 7/10/16 my internet stopped working. The router blinked in red and this morning back to green, still blinking, but no internet yet.

I can't reach customer service through the phone.
I did pay money for this month of October, and in Meine O2 it shows my contract is still ongoing and that I have an update invoice. know what

I need to know if it's technical or contract issue.
What can I do?

All the best
Gali