Car play scrambling maps!

Please help! I’ve recently bought a car, apps worked perfectly with my iphone to CarPlay via a USB lead, but suddenly all apps are scrambled, I can’t see maps at all any more, I can still hear sound perfectly, but the screen is dreadful, I’m so disappointed… there seems to be very little information on this subject, I can’t be the only one! I’ve tried turning everything off and on again, and my phone is up to date.Who is responsible for this? VW / Apple / infotainment system company? How do I go about getting this fixed? How much would that cost? I can provide photos if necessary