Hello,
Karstadt Oberpollinger at
Stachus have a large fabric section; it's in the basement of the new bit. They stock quite a few patterns, including Vogue, Burda and Butterick. If they don't have your size in stock then you can order it and it gets posted directly to you. The last time I was in there, the sales assistant was really helpful too!
There is also a quilting and patchwork shop in Sebanstiansplatz who stock loads of cotton fabrics. I usually have to be dragged out of there by my husband...
Bron