I believe consensus would lead you to look first at the various summer and short courses offered directly by Jagiellonian University. They are grouped by level and are excellent (is what I've heard - I've never taken one myself). You can find information online:
Merged: Polish for Foreigners Course in Krakow. Has anyone attended such a course?
Has anyone attended such a course in Krakow? Are they any good? Prices vary hugely it seems. From as low as zl650 for a 44 week semester course. Anyway any help would be much appreciated as I have been here five months and the self study, impatient girlfriend route doesnt work.
Have you tried just having private lessons, you can do this fairly cheaply if you look around. I did my lessons over Skype, and I would argue it beats the hell out of doing it in a class. The teacher will suit the lessons just for you, you aren't slowed down, and you always get the chance to speak and not wait for others to catch up. Plus being in a class with other English speakers beats the point unless you all force yourselves to speak Polish (Which is difficult).
That being said, the only thing missing is the social aspect of it.
I spent 2 weeks of August in Poland, Cracow (Krakow) learning Polish and it wasn't that expensive (it was about 400 euro for the whole course). The school was great, so was the book and my teacher. I took a very intensive course and my group contained only 3 people. After classes we usually went on a trip with Polish guides or grabbed a beer during Pub Evenings with our teachers, so we tried to speak Polish all the time. The book's name is "Polski Krok po Kroku" (Polish Step by Step), you can buy it on the Internet. School's name is Glossa in Krakow.