Haven't had any problems with these they do what they say.
Punctured on only my second use (on not particularly rough roads/tracks). Self repair failed to work and I had to walk home and resort to the good old puncture repair kit.
I'm sorry to read that the innertube did not seal itself. Holes made by thorns, small pieces of flint or small pinch flats should seal up with no issue as long as you keep on riding (important not to stop riding), the motion of the wheels spinning plugs the hole. If you continued to ride and the puncture persisted, the hole may have been too large.
If you believe the item to be faulty then please feel free to return it to us for a refund or an exchange.
Peter Lazarus, National Cycling Manager, DECATHLON