I recently purchased a 745i after owning a 740 for 12years. Took into bmw as speakers on drivers side not working. After a diagnose the tell me ask unit in dash is faulty, They wanted to replace the unit with a new one at a cost of $2500. I removed unit cleaned and replaced and it worked but only for a few minutes . I need to know who in Auckland could do a repair as it seems some component is losing power?