1 other person in the entire world having the same problem as you is not conclusive proof LOL. In the same way as plenty of happy ktec customers (I gather they all exist on this Renault UK club thing) doesn't prove that you're not having issues.
But that's irrelevant because I still kind of agree with you. "Cheap" doesn't necessarily mean the manufacturer can't do the maths/theory to pick spring/damping rates just as well as AST (gold dust as far as CS is concerned). The Engineers at Renault will be no less qualified or experienced than the Engineers at Aston Martin for example. They just have different budgets to make the same thing. Cheap just means they have little control over the damping rate that the damper actually produces. Whether that's poor manufacturing tolerances, seal packs that are prone to leak, a batch with not enough gas pressure blah blah blah you end up with an "under damped" rear suspension.
Out of curiosity, would you call it "skittish"(cause = springs are too hard) or does it just "continue to bounce for ages" after hitting a big bump (cause = not enough damping or too soft springs + sensible damping)?
Sell them to someone who thinks "lows" are "sik" and buy some low mileage second hand Bilsteins, Gaz, AP, BC etc