Slow response and delivery longer than advertised

I have purchase a dress on 29 Nov 15 and received confirmation of payment. I have received an e-mail on 1 Dec 15 to confirm that the order has been packed and the parcel was handed to the courier. On 4 Dec 15 I phoned to check on the status as no further information of the order was received. It was confirmed that I will get it on Friday (4 Dec15). I have not received it or any feedback to date (I have also e-mailed them) and the phone lines are so busy you don't get through.