On the north side of Cartegena is a massive shopping park, just off the AP7.
The Carrefour hypermarket has the most amazing selection of just about evertything you can think of, from White goods to the widest selection of vino i have ever seen.
A few doors away you have Media Mart which makes Currys look like the old corner shop.
Next door just about to open was aonther electrical store, so well worth a visit if you still need to buy any stuff.