Dash lights not working at all?

The dash lights/warning lights/gauges have completely gone out. I’ve taken it to the Chevrolet dealership where I bought it 4 times now and they have no idea how to fix it. They actually told me they wouldn’t be able to diagnose or fix the issue while the dash lights weren’t working. I mean seriously?? That is the problem. I can’t even see how much gas I have at any given time. The check engine light comes on every once in a while, but even that much is scarce. Also, the lights aren’t flashing or anything like that either. They’re completely out and have been like this for almost 3 weeks now.