RE: Weed and Grass REMOVAL
The roundup will kill the weeds eventually - its what I use on mine. It can take 3-4 weeks unless you are using the fast version, which still takes about a week. It will definitively kill them but won't keep new growth. Products are available for the latter.
It's actually good that you used roundup and waited a few days for tilling. Now they should be good and dead. Good luck getting your money back. Any garden department will tell you roundup takes weeks to kill, but kill it does (unless you have genetically altered Roundup ready soybeans growing on your track!).