Handy guys: what's your suggestion?

Sorry I can't upload a pic but...

My dad messed up out walls. They were white paneling. He wanted to fill in the panel lines/grooves but used some caulk crap and did not smooth it out.

What can be used to fix this?
I've already sanded down as much as I could. It's still bumpy and you can see even thicker caulk lines.

Considering just getting more paneling and putting it on top and painting nice color...

Any other suggestions?