Never will I fill up again at total R27 Melkbostrand Cape Town

So I went to Total garage on the R27 Melkbosstrand yesterday to stop and fill up before continuing my journey. The attendant came and filled up while I went into the shop. I came out and got into the vehicle and payed him. Only when I reached my destination a few hundred kms later, I saw that my petrol clap and top are still open.