Hello fellow asshole enthusiasts. I live in a small apartment building. Above my husband and I lives a single mom. Earlier this year we had the internet installed and set up a second wifi connection for our neighbor on the condition that she pays us $40/month. She approached us with the offer and the amount and my husband and I agreed. 

At first everything was fine and dandy and she paid when she was supposed to, then she was a bit late then only paid " half now half later" and then just stopped paying altogether. It's not like she is hurting for money, we see her come home with bags of stuff from the store on at least a weekly basis, got a new car this year etc. When I see her outside she doesn't mention anything like " oh yeah I owe you I forgot, I will get your money now". I don't feel like I should have to chase her down to get the money she owes us. 

My husband and I make a decent amount of money and we easily can afford and have been paying the bill ourselves, we don't NEED the money ( it's not going to make or break us every month) but we are saving for a mortgage and have two children of our own. 

WIBTA if I changed her wifi password so she can not connect until she pays us what she owes ? 