My experience against C3 (and C3i) is that you really have to push jammers forward to disrupt the lines of communication, either cutting off spotters, breaking up C3i nets, or getting into the main axis of someone's advance to isolate people from the masters. Without jammers, you need to be pushing hard to get your forces right in someone's face, killing spotters as you go and doing your best to get to the master(s) and kill it(them).