General Annoyance

So, we live on the bottom floor of our apartment complex. Just after moving in, we went to meet the neighbors that live above us for two reasons: 1. to give them an opportunity to welcome us to the neighborhood (we figured they wouldn't do that without some coaxing) and 2. because we heard they allowed everyone to piggy-back their wireless internet. They seemed pretty nice, besides the fact that the wife has a striking resemblance to Skeletor (I'd like to take credit for the He-Man reference, but Katie was the first to point it out). They charge us $15/month to use their connection. We don't mind the cost too much, but according to my calculations, they're making out like bandits if all 8 apts use their internet. Shortly after our first visit, though, we discovered that we could hear just about everything Skeletor and the Master of her Universe were doing through our ceiling. That sounds markedly dirtier than I meant it to, but.......We have no idea what they do up there at 4 am, but here are a few options of what we think it sounds like: blind-folded roller derby, greco-roman chocolate pudding wrestling, the new Billy Blanks tap-dancing Tae-bo video, etc. They also get really irritated if we make any noise. Any time I put a nail in the wall to hang a picture in the middle of the day, they bang on the floor as if we are disrupting their invisible sleeping baby. We sometimes turn on music on Saturdays while we clean the house and they always turn theirs on louder so they can't hear ours. The icing on the irritating cake came when I got en email a few weeks ago from Skeletor's weasel husband because we hadn't paid for May's internet yet. I got it on May 2 and somehow it got erased, but I'll paraphrase: "I'm sick of you paying for your internet late. I have to pay for the internet on the first of the month and so should you. From now on, if I don't get your payment by the 2nd of the month, I will disconnect your connection. I'm tired of waiting for you to pay." I decided to take the high road and assume that they were having financial problems and that was why they needed our payment. So I wrote a check for 3 months worth of internet and went to talk to my confrontational web admin. Surprisingly enough, he sent Skeletor to the door to deal with me(I know he was there, I heard him hiding in the kitchen). Undetered, I offered to pay them the last week of the month so that our check would clear in time for them to pay this ominous internet bill. They declined. I'm not sure how they'll react in 3 months when its time for us to pay again, but you'd better believe I'll be knocking on their door with a $15 check at 11:57 pm on the night of the 2nd.