How to get internet-connection being new in Vienna

Hello!
I have just moved to Vienna and I am trying desperately to get internet connection which looks impossible at this moment because I have not been here for at least 3 months. I have a prepaid mobile internet now, very expensive and of extremely bad qualitiy, so this it for sure not the solution for long term. Can you advise me on how to get a quality internet connection in my flat?
Best wishes,
Csilla