Give me my money!!!! common sense and bad manners

Why is it that when a muslim is employed by another muslim, they are relaxed when it comes to paying their muslim employee? If it was a non-muslim they would pay them on time, but when it comes to paying their muslim employee they think its ok to delay it.
A few months ago, a muslim sister called me up (shes a foreigner), and told me that she needed to talk to me about something. Worried, I asked her if everything was ok. She laughed and said yes. She asked if I was free the following day (Saturday) and I told her I had no plans and could meet her in the morning. I arrive at her house around 10am (she asked me to come early), during my drive to her house I was trying to figure out what she wanted to talk about (we are not close friends, and barely talk).

When I get to her house she ushers me in and asks if I am hungry, I say no (I was on a diet at that time), and I sat there for a few minutes chatting with her kids (ages 5, 10, and 12). She left the room for a few minutes later and when she returned she was wearing her abayah and hijab. Confused, I wondered where she was going. She then came and told me that she had an appointment and wanted to know if I could stay for a few hours to watch her kids. Excuse me, I thought, did I just hear you correctly, watch your kids?
Confused I said ok (I couldn’t lie and say I was busy since earlier I had told her I was free today with no plans). She then told me she would be home in a few hours and grabbed her keys and met her husband in the car. I then turned to her kids and asked her where she was going. They said they were going to a friends house…. I was beyond shocked and pissed! Is this why she called me over, to babysit?

Why didn’t she ask me on the phone if I could babysit? Why did she act like she had something important to tell me? Not once did she mention anything about her kids or going anywhere. I felt betrayed…..Now I was stuck with three kids for 2 hours…….. 4 hours later they returned…. The mom nonchalantly asked if she should pay me (first of all, you don’t ask if you should pay the person, you give them money and tell them to take it). I of course felt awkward saying sure, pay me! Instead I said, its ok don’t worry about it. She smiled and thanked me and then ushered me to the door……
During my drive home I was still in shock over everything that had happened…. I was so angry that she lacked any common sense or manners!

That brings me back to money… It’s been a month now and the muslim sister I work for (I tutor her kids), has yet to pay me. I have tried to bring it up a few times but each time she tells me she will pay me “tomorrow” and when tomorrow comes shes either not home or she doesn’t mention it and I felt awkward reminding her again……. Any advice would be appreciated.