The new Endesa office can be found just past the Rocasa shop on Av Juan de Bethancourt in Puerto del Rosario. Take the next turn left and it's at the junction of Calle Sevilla and Calle Los Homiga.
http://maps.google.com/?ll=28.504381,-13.867002&spn=0.001358,0.002642&t=m&z=19 (http://maps.google.com/?ll=28.504381,-13.867002&spn=0.001358,0.002642&t=m&z=19)