Although they both stopped working at the same time it is worth looking at the wires inside the rubber between the rear doors and the B pillar. Just pull back the rubber from the door plug and all will be revealed. Mine were broken and a quick job with crimping connectors cured the problem, and gave me better sound from the rear speakers :) I made the mistake of replacing the entire loom on one side, not only very expensive but totally unnecessary as I later discovered.