In reply to Gibson:
My normal approach to anything like this is to make their lives impossible until they sort out the problem.
Fill their facebook page with complaints if they have one. If they ban you from the page, rope in friends to assist (just make sure you dont slander them)
Phone them incesently for an hour.(withhold your number) phone every number they have every minute or so. Make it so that no other customers can get through. Perhaps ask to wait if they insist you need to talk to a manager etc.
Record details of the calls, who you speak to etc.
Contact trading standards etc as well, bombard their website with email complaints, if possible get or guess at the owners address and details.
If you can visit the shop in person, stand in the doorway, and calmly refuse to leave or let any customers in.
Normally just being a pain in the arse will get the problem sorted.
If I were you I would demand at least 10% further discount on the price, as the item has now clearly been damaged and is not in the state it was when you bought it, or some form of compensation if you go for a refund