Very bad service

We've rented a car for 3 months with 1first (Nissan almera). Recently, we've had a brake problem and we called 1first to ask them to change the car. We went first to pietermaritzburg, and they said they didn't have a car big enough. So we had to carry on with our problem'for a few days, till we get to jhb. We called the agency there before coming, telling them what car we needed as we had many luggages and 3 kids. They said they would make a plan for us. We arrived at the agency in or tambo at about 6:30 pm after a long trip from'the drakensberg. When we arrived, they didn't have a car ready for us. They said a few times that we should wait for one coming from a warehouse a few kms away from the airport. Wait for 10 min, again and again... The 3 kids were hungry and tired, the baby was crying, we were all waiting in the underground, sitting on our luggages... We went a few times to check what was going on, but we just had to wait, the car was on his way,..... Till after 2 hours (so between 8:30 and 8:45 pm we finally got the car...<br> We don't understand why it took so long, as they knew about it before we arrived, and we could see many big cars there that could have suited us!