Bad service/wrong order received

Where to start... Second time... Worst service!! You know I'm great full for delivery service but if you don't know how please don't say you can! I placed an order at 11:49 delivery time was set for 12 ok they didn't as I understand the industry ok so I logged in to see and delivery was moves to 13:00 ok no problem they might be busy then I logged in again delivery was moved to 14:00 and phoned in to here what is going on and they told me delivery is on its way I had to leave and I left my husband to collect as I couldn't wait any more I had an appointment at 15:00 so after a while a logged in delivery was move again!!! Then a delivery did came but it was not mine!!! I phoned in Again and my order is still at the shop and I'm sitting with someone else's order!!! Phoned in and customer service trying to get collection and delivery but it's now 15:50 and I don't know if they will still deliver so how do one get spared of the humiliation of people coming over and I don't have my order if I have known I would have gone to shop and get it myself if I didn't have an appointment, I used R60 wurth of airtime and a lot of frustration. On top of it all the second time I logged in a free delivery code pops up so you can just imagine how angry I got as I could have used it so why didn't it pop up the first time???