Hi,
You could try BRICOR - it's like a smaller B&Q.
If you take the coast road towards Marbella, it's on the right a few miles past Estepona.
The sign is yellow and easy to spot, but usually once you've passed it, so you may have to double back.
Either that, or if you find it on Google you could get the Km marker and come off at the correct junction?
They have a big stock and bathroom stuff seems to be their speciality.
Tom