One practical routine that keeps my soy jars from tunneling is simple. I only light when I have enough time for the top to reach the sides, I trim before every light and I keep the candle away from vents and open windows. If I forget and a tunnel starts, I do a single long correction burn with a loose foil collar and it usually evens out in one go. With your current candle, do exactly that. Tidy wick, quiet spot, long burn until the surface is fully liquid, then let it set flat. It should be back on track.
