It mentions monopolies as a problem, but then offers no solutions to it

The site has specific solutions...

It’s time to rein in the monopoly sectors that aren’t competing to bring prices down - like our supermarkets, banks, building materials and power companies. It’s not right that these businesses make record profits while ordinary Kiwis cut household budgets and our economy stalls. To save the average Kiwi household more than $40 a week (projected) and boost competition and growth in the wider economy, Opportunity will:

• Bring power prices down by reforming the electricity sector.
• Bring other prices down by breaking up or regulating the cozy mock-competition among the big banks, building material suppliers and supermarkets.
• Strengthen the Commerce Act and boost funding to the Commerce Commission.

Detailed policy is coming, they are looking at this issue. Both major parties have taken a pass on this; what more are you looking for?