Ban all political donations
Lets align political donations with votes. Give all voters $100 voucher that they then donated to the member of parliament or party they prefer. And ban all other donations!!
This would make sure that politician only represent their electorate. Not big business, not interest groups. Business and interest groups can all lobby voters and promote their own causes. But the people decide and the money comes from the people only. This will make sure the politicians only work for their electorate and not any other masters.