Not value for money the edges don't stick down properly

Based on my previous purchases from InvisibleShield I had high expectations of this product on my new Samsung S8. Though from the time I applied it things haven’t been the best. Okay, the application instructions were good, but the website video showed a different application technique!
I followed the application instructions to apply the face of the screen protector, then the sides, but found that the sides stuck at first then lifted, I pressed them down again, and they lifted again. After a fair amount of time pressing and re-pressing the sides of the screen protector just to watch it unstick again, I gave up in defeat. I now have two dust coloured lines down each side of my screen where the unstuck screen protector has collected all kinds of dirt and dust.
The disappointing thing is that the same thing has happened to my son’s S8 (I purchased both screen protectors at the same time).
I thought that InvisibleShield would have designed a better product given they had already produced a curved-edged screen for the Samsung S7 Edge.