I have the Telefunken TICES-719BTGPS. The insaller says there is no Aux or USB function for the radio, even from the back Yet the specs and user manual says it does have that. I know the device doesn't have a direct aux or USB input from the front but from the rear considering my car has a built in aux port in the armrest I think that this should at least be able to be made functional. any ideas and perhaps the installation manual if possible please