frustrated

I placed an order on the 28th of March on Mr Price online and chose the express delivery option which is more expensive but needed the items to be delivered promptly.Today it is now the 1st of April and the status is still sitting on shipped whereas a colleague of mine has also placed an order online but on the 29th of March and chose the economy option and she got an email to say that her order is ready for pickup at the store.How is that possible when I chose the Express delivery and placed the order before her and my stuff is still not ready.It makes no sense to me so I have to pay extra for an express delivery but the economy option is quicker and cheaper. Will not be placing anymore orders online as their service delivery sucks.