Is this how you treat customers?

Last week Tuesday I ordered a Manchester City Junior jersey to be delivered to the store and it got there on Friday. I went to the store for pickup and I realised while I was there that the size was small and asked for an exchange. Another online order was placed on Friday at the store and the cashier insisted to be delivered to my residential address. I told her I need it before Friday as my son's birthday is on Friday, she said it take 3 working days. All I can say is even after 5 working days I did not receive my order and I'm extremely ****ed because I couldn't give my son his birthday present. Today is Saturday and I still haven't received my parcel, all I got was a message from the store manager to say I must phone the courier company