Still waiting for an online order to arrive after 9 days, you have stock on the floor yet wont let me take it

I placed an online order on the 9th of December for a pair of slippers to be sent to Blackheath Cresta from Crown Mines. I received a message on the 11th of December to say the order was on its way to Blackheath. on the 18th December that order has still not arrived! You now have stock of those slipper on the floor at Blackheath Cresta yet I am not allowed to take a pair off the floor and must carry on waiting for this order to arrive when I have already paid for it? I'm sorry but how long am I expected to wait for this order ? It has been a week since it was on the way to Blackheath.