Welcome to Flyer Talk leanne03

Travel on Circle Pacific to/through South America requires the 29,000 mile fare. In any case, because some of your legs do not have direct flights you will need the extra mileage (every flight counts towards total mileage and also land travel also counts).

Alternatively by rearranging slightly you could do a 5 continent one world explorer, which has a bit more flexibility albeit at more cost.

Any airline included on the itinerary, or any travel agent, should be able to help you with this ticket.