Missing baggage United airlines

I’m very disappointed in the service received by United airlines. I arrived from a flight from United States on Sunday. When collecting my baggage my one bag was missing. Two days later they phoned me and said the bag has been found they will deliver it. Shortly after that I received another call saying i need to come pick it up from the airport OR thambo. Now i am confused it’s not my fault that my bag went missing now i must drive up and down to collect it