Guy, I saw the rep today, that gear is more expensive than I remembered, £25+ the dreaded, If you want some Ill PM you his number, he can take a credit card payment over the phone, and get it straight to you
My guess is that your windscreen may have some sort of contamination, possibly silicon based polish that you are only moving around, and not removing, when you clean it, also some adhesives need UV to set, and some must not get any UV at all while setting!
Tom