souq waqif car park

Now, do tell me how you would react in this situation. This has happened to me twice, and both times I took the path of least resistance, but wonder if I should have been more assertive. First time was at the souq waqif car park and second time at the Centre/mega mart... >

I am looking for a parking space and driving around. There are not many parking spaces. I find one. Then I see a person standing in the middle of it, on their phone. I indicate to them to move to the side. They wave their heads and say 'no'. I open the window and say, "What do you mean, no??!!" They say "this space is reserved. My friend is coming. I am keeping it for him".