First thing to say is.
and commiserations!
Have you contacted Suplex about the issue(s)? If so what is their response?
From my experience and knowledge of the system I know that initially Suplex had issues with the front springs fracturing after a while. To combat this they softened the front springs. Unfortunately this resulted in a very soft wallow-y ride, low ride height and clonking issues.
The issue could very well be low ride height. At what height have you managed to set the front suspension?
With the original springs supplied to me, I couldn't achieve anything like the recommended 350mm ride height. (350mm from wheel centre to wheel arch; vertical height)
Before Suplex stopped talking to me altogether, they supplied me with rear spring canisters for the front. These give a good ride and no clonking but the ride height is too high.
I have managed to achieve an acceptable ride height with these rear cans all around now, but I'm not prepared to post how, on open forum after the shocking way I was fobbed off, by the managing director of Suplex.
If you end up with rear cans for the front, please PM me. I'll let you in on the secret.