We do have a problem.
You might look at this as a criticism of yourselves, and I don't really mean it, but a big part of the problem of the weakness of Parliament vis-à-vis the executive is the dominance of parties over almost every aspect of an MP's existence. That's not the private side in dealing with the constituents, but who participates in committees, in question period, who gets to talk during a debate, and so on. If you're a bad boy, you don't go on a foreign trip because the whips want to punish you.
If I were to suggest the one obstacle to a collective voice from Parliament in looking at things like the budget and making even minor changes, it's that dominance of party and the control that party exercises over the parliamentary activities of members. I don't know how to break that, and I'm sure you could tell me far better than I can how you might do that.