Online order gone terribly wrong

I placed an order online online which was delivered on 11 April (Sunday) instead of Saturday. I didn't receive any kind of communication notifying me of the delay. On receipt of my order, just after the delivery guy had left, I noticed that my order was short. It was already after 5 when i noticed so i only called them on Monday only to be told that an investigation will be done. I followed up today (Wednesday) only to be told the same thing. What I wasn't aware of is that they were saying that I will only get my item after the investigation which I don't get. I feel like I'm being investigated here for their mistake. Why can't they delivery my item while they do their investigation. I then asked if I can get refunded for that item so that I can place a new order and they said that will take 7 to 10 days, again why am I being punished. The only thing I wanted was those shoes.