FT is not a travel agent nor have a source of cheap tickets.
Upgrades are never guaranteed, even if you have ff status with the airline.
Some low cost fares can not be eligible for upgrades. Depends on the airline
If you 100% want to fly business class buy the ticket with ff miles (award) or cash money. Or direct with Chase points if that is possible (I have no idea)
Chase thread
Ultimate Rewards - Airline and Hotel Transfer Partners, Rules, Timeline, etc (2017)