Chances are you are using either Jungo, Bezerk, Freaks, Fang Pi Clang, La Junta, Skeelz, Pussycats or Vortex. Nellie and Herman overpower those clans in general very strongly so changing your deck or half of your deck and adding a clan that isn't from the list I have mentioned. Fight fire with fire use Powerer Manip cards against them. Prince Jr, Tobbie, Tula, Platinum, Wesley, Allstars even. Attack Manip cards are also strong against Power Manip so cards like Nimestic, Corrina, Raeth, Sargh cards like that can make them pill and pill for pill can have more attack for a substantial ammount of pills. Ofcause the most obvious solution is to use a protection power card like Mantiz, Melanie and Fixit.
All cards mentioned are under 10k so take this advice and make which ever deck you feel will suit your playstyle more.
I suggest Sentinels. Lehane, Martha, John can take them out. And yup, they're relatively cheap. Problem is Martha and John are more for mono-Sentinel though, that may limit your choices a little.
Ahh one more thing, you might want to put in a Leader like Hugo or Ambre to even things out a little bit.
Hope I helped, cheers!