They produced the "Grossery Gang" as a continuation series to the Trash Pack, but the oldest Grossery Gang wasn't so good and they stopped making them.
I think because the new series they were trying to produce didn't created such enthusiasm as the first Trash pack did - so they stopped making them at all.
The last series of the Trash Pack also wasn't very successful.
And I honestly think the Trash Pack is much better by far then the Grossery Gang, although I collect them too. The design and the quality of the Trash Pack figures is much better!