The language has changed to Spanish - how do I change it back to English?

Enter the setup mode, by pressing and holding the play/pause button while powering your car kit on. You must complete the four setup phases, where the first one is precisely the language selection, for your settings to get saved. Browse through the options available for each phase by pressing the volume up or down buttons, and select the option which suits you better through the play/pause button. For each selection. the indicator light will flash green as a confirmation. Upon completion, your car kit will play the standard power up sound, and will start as usual.
Hope it works for you.
By the way, if you car kit's user guide happens to be missing, feel free to download it from this location.
Anyway, please, let me know if I can assit you any further.
Regards, Carlos