question about receipt of termination request

I had moved out of Germany a few weeks ago, and sent my contract termination request and documents a few days ago. I have received confirmation from the courier that it was delivered earlier this week, but have not received any update or confirmation from O2 about it. Since the document itself said it would be processed on the next day, I wanted to check if there is any way to know if it has been received and processed yet, or if there was any problem that I need to look at.