https://www.openstreetmap.org/node/10945798161

The address is Lwowska 15, not 15a, unless the café is located in that ruin facing Lwowska. Check geoportal.gov.pl for official addressing; if there is a mismatch, it'll need to be resolved with local govt first -- OSM follows official address registries.

Also, if you happen to know the proper spelling of the name, do correct the node I've added. The owners appear to use five different names, with different capitalisations and spelling of the word 'café'. 