Faulty head unit. Potential upgrade options? Not sure what to get.

Hi, 

I have a 2014 Skoda octavia fitted with a 5e0035842a and 5e0919605b. 

The screen has been flickering for a while and its been back to the garage twice. They say they can't repair it so have offered me 2 options. Pick a new aftermarket unit or pick a second hand OEM unit and they'll pay for it and fit it for free, including any coding required. They've given me a budget of £500

I would prefer to keep it OEM if possible but would also like the idea of Apple Carplay or Android Auto and sat nav if possible with a slightly bigger screen than it currently has. 

Does anyone know what options are available? I've a had a look and I'm confused already, lol. Is it just as simple as replacing the 2 units with something from ebay.

Thanks,