In some ways, you are lucky to have 2 parties.
We have, at the moment, 3 parties, working together [sometimes] as the ruling power.
Then the power plays is "if you want our vote, agree to some outrageous idea of ours, or we won't play the game".
We have 3-year terms, with no limit to the number of times the same person can be the leader, if their party wins the election.
they rarely last to a 4th election.
We also have the so-called "original inhabitants" [the equivalent of the Indians]that have a set number [4 out of 120] of seats in our single level Government, and their own party as well, they can also stand for election in any of the other seat and parties.
The Maori were given millions of dollars in reparation for some land grabs in the 1800s, an audit of the books found that one of the leaders of the party managed to spend over $100.00 on a pair of underpants, just 'cause he could"
One possible way to correct your problem, it would be a bugger to controll, limit the amount anybody cauld give a party as a donation, or, print in a/all newspapers, who gave what to who. so everybody can see who is buying what.