Bad service

I am very disappointed with the service I received from G-start at Mall of Africa, first of all the guy who assisted me was unfriendly. He intentionally gave me the wrong size, because they wanted to meet their target. I asked for XS, but he gave me medium. I got to see it when I arrived home. When I checked online stock availability, it showed they don’t have XS. I need G-Star to arrange and pick this up, and give me the correct size, because I don’t have petrol to run around. The name of the cashier is Lehlogonolo or Sandile, he is tall and light in complexion.