Issues regarding my phone bill

I am not able to understand the bill. I got my internet connnection activated on 8th December,2016 and my bill is 51 euros.Secondly, my internet is still not working. Due to some urgency,  I have to leave Berlin for 3 weeks and that is why I was not able to complain about this issue. My line is still not working and I have received an invoice of 51 euros.