Input welcomed

This may be a little long, it's a mixture of rant/looking for advice. No idea what room this goes into.

We live in an apartment complex and we are having issues with our downstairs neighbor. She loves to party. Sunday night? Party! Thursday? Yea party! The music is loud, late (after 10pm I'm talking starting at 11 or midnight and going until 6 in the morning) the people she invites over are loud and yell outside, and so much pot is smoked our apartment smells like it. We have a 3 month old son.

When it started we did the polite thing of knocking on her door and asking for it to stop, I was pregnant at the time. She was nice to my husband but after she closed the door we could hear her loudly making fun of us to her friends. Either our walls are thin or she is just loud. The next several times we called the office to complain. We've called the cops once on her but I feel like an ass doing that, but nothing seems to get her to stop partying so late all the time.

Well I was just woken up, at 4:30 am, to her and friends yelling as they were apparently coming home. Doors slammed and the loud heavy bass started. I can hear their conversion in my kitchen. What in the hell do we do? Do we just let this continue or keep calling the office? It's ridiculous and the most rudest neighbor I've ever experienced.