Hi, my name is***** your mechanic automotive expert, and I will be happy to assist you today. In some cases, I may need more information to assist better. I apologize for any delay.
Dear customer, I think that it is a problem at the equipment configuration level, many clients come asking for questions when such problems arise because they accidentally manipulate some settings and deactivate the speaker output.
You have to do a very simple test, place a person who manipulates the equipment while you place at the level of one of the door speakers, if when you touch the screen to navigate, you hear sound coming out from one of the speakers, the problem is configuration and the horns are correct.
If it is getting sound, it isnecessary that you locate a diagnostic equipment with Corsa software to perform the factory data reset of the equipment and with this leave the initial settings.
Now, there are ways to do a factory data reset so you don't spend those 100 pounds at the dealership, I recommend you go to a car audio or electronics garage as they work with the installation of sound system equipment, GPS, SAT nav etc. this kind of garages know this equipment very well and can perform these configurations and revisions at much lower costs than the dealership itself and can do these reset procedures themselves.
My goal is to give you the best advice i can based on your description, I hope to be helpful, if you have any doubt please do not hesitate to reply back.
Kind regards, Sebastian.