15% of income post tax is incredibly steep. Why wouldn’t someone just pay $8k upfront? If you plan to actually use the service and get placed with a half decent salary, any of the other options are a complete rip-off.
Many who might be interested in CodeBreakers fear investing $8k and end up with nothing. That's why we offer the ISA option to work with everyone's budget. Candidates planning to use the service seriously to get placed are encouraged to choose whichever payment options that works best for them; that's why we have both options.