It's the first time that I've had to collect anything here in Cartagena but there was an address on the slip - Calle Submarino, 63 - just up the road. There is a Post office at Submarino, 63 but it's new and it's not open yet. I wandered around a bit with the distinctive yellow and blue slip in my hand. A passer by took pity "The Post Office is just up there, turn left by the Pharmacy." I did and there it was but at number 4, Calle Santa Teresa.
Bit of a joke really.