2006 attempted immigration reform. You asked for one example and there it is. Bush and Congress wanted it, the grass roots lit up the phones and emails and they thought better of it. Holding their feet to the fire is not just crap.
Yes, that is one signature example of successfully 'holding their feet to the fire', but you'd be hard pressed to come up with many others.
Our side seems to require the most dire sorts of threats to get motivated enough to give our reps hell. In the normal course of business, wayward Republicans do whatever they want, and don't bother themselves with what the folks back home think.
If we were really all that good at keeping them on the straight and narrow, we wouldn't be having this interminable fight over ideological purity vs political pragmatism. We wouldn't have our guys wandering off the reservation to the other camp at all, and the word, 'RINO', would rarely be spoken.
Until millions of us are pissed off enough to camp out in DC til the traitors surrender, it's all just talk.