I have a problem with the GPS signal inside the car. Sometimes I lose the GPS signal inside the car, and after navigating the car, but also after any phone, no matter what phone or application I use. It has moments when it happens, in a year it happened 3 times and lasts 3-4 days. This is an Audi A4 from 2010. I went to Audi for investigation and they told me that I have to change the whole unit which costs 3000. I am sure there are many other cheaper and simpler methods. I even want to eliminate the navigation function after the car, I can use the one after the phone. Audi said that if the elimination of navigation is done with a radio, music player, etc. Solutions please.

I'd be trying a second hand unit before buying a new one as I'm sure Audi wouldn't diagnose it incorrectly.