Any bad experiences with your maid/nanny? How did you deal with it?

We tried to get a nanny for my first born when he was 3 months old, when I was about to go back to work that time. I started training her while I was still on leave. However, the first few weeks were already horrible. She doesn't know how to follow simple instructions. And when he was looking after my son while I was checking something on the computer, my son fell to the ground because the nanny was dancing (saw her reflection on the mirror) instead of hold my son. My son's gums were bleeding when I picked him up and his face was all covered with mud. I didn't have second thoughts but to quit my job and be a stay at home mom from then on. I'm not getting a nanny again ever.