Wrong order sent, customer must suffer the inconvenience

I have just received the most pathetic customer service from fox clothing/zando. I placed a order for a pair of mtb shorts and shirt last week, I received my order on Wednesday. When I checked my order to my surprise I ordered a size 34 pants, but received a size 40. I phoned and queried straight away to lodge the return and to get the correct size to me. Due to slow courier services the parcel was only collected on Thursday. Come today, Friday I have to phone to find out where my pants are, I get told I might have them next week. After numerous calls and having the phone put down in our ear we get told there are procedures and quality control checks that must get followed, if these were followed the first time then I would have the correct product the first time. I feel as a customer who did everything right, I am getting punished with not receiving my order because of poor control on their side. These were expensive pants and were ordered fora very specific event taking place tomorrow morning. They have advised us that there is no way possible I can get it today, this was not my fault, why must the customer suffer the loss.