Sod them. It's your Wifi and yu protect it how you see fit

I'm just amazed you didn't password protect it earlier. Sure, they're dicks for being upset about it, but surely you knew people were using it?

Must feel good to cut the freeloading bastards off.

Since you've cut off everyone else in your apartment building, and rightly so, your wifi speed should increase.

Well time to get new wifi? or you could make a new user to access and delete the other one.

YDI - But only because you waited so long to password protect your wifi.

I had a similar problem with my internet at home a few years back. It was super slow and laggy, and finally my family and I figured out that several of our neighbors had been mooching internet off us. We promptly got a new wifi server set up and added a password to it. Funnily enough, one of our neighbors got their own internet later on, and I happened to notice they'd named it "yousuck." Can't help but feel that may have been directed at us. I found it hilarious.

So your first indication was it running slowly and not the internet bill that must have been super high?

Imagine how much extra bandwidth you've been charged for from them browsing for past couple years.. Think, a single movie is like 3gb in bandwidth when streamed on average

Ask them if they pay for it. When they say no slam the door