diberry - 6:07 pm on Jun 7, 2013 (gmt 0)
although I know most here won't believe me I haven't indulged in any shady practices so I'm not entirely sure how I can recover or improve
You're not alone. It sounds to me like it's a waste of your time to keep trying to please Google when you can't know what they want, and Bing is doing better for you anyway.
I was hit last time by Phantom update on May 9
Phantom update? Do you know anything about this one? (I gained traffic from it, significantly, on a Penguinized/Pandalyzed site.)