That new roundup gel

Hello - has anyone else tried that new gel that is advertised on tv?  The one where you are meant to simply dab the leaf of a weed and then it's meant to kill said weed right down to the root?  I've paid over £8 for this stuff and it hasn't worked on any of the various weeds I've tried it on.  Bad bottle maybe, or has anyone else been disappointed with the results?

Unlikely to be a bad bottle-the results are not instant-when did you apply ?

You should see the affects in around 2/3 weeks-be patient!!!