Straight off the train from the airport, Galeria Krakówska, walk in from the train station, take your first left and it's on the right hand side. Most staff in the Galeria can speak English and you will have a micro sim in about 30 seconds (as long as there's no queue). As them for a leaflet about data charges and top up your phone, then text the code to number on the leaflet and boom...within 20 minutes you have unlimited data for 30 days for all of 10zl!
[The text message you get back will say it will be active in 24 hours, it's never taken more than 20 mins for me]
