My bill is incorrect and i cant

I have to start off by saying my German is not good enough to have this conversation with the service team and it's so frustrating. I paid my bill since January only for my invoice to read that I have outstanding. I tried to call and luckily I was put on with someone who understood English, we were able to identify that the reason is that I did not put the customer number on the payment - I had forgotten. But I was able to identify what reference I used. Unfortunately we could not do anything about it that day because they were having issues with their database. The guy said I should call back on Friday and I did but unfortunately he wasn't the one and the lady who answered did not speak English. Now a month later my internet is cut off because of outstanding balance that i have already cleared. There is no email to contact, what can I do? I can not even call customer service  because no service to my phone. I work from home but I can not work because my internet is cut off too. It's not meant to be this hard

Edit o2_Kathi 12.02.26 Moved from the section o2 Mobilfunk to English o2 Community