You need to read the fare rules to be sure - if it is made up of multiple fares, then there may be a change fee per fare component or maybe not - it depends on the rules
If it is a AKL-MNL r/t fare , then would almost certainly be $200 for all changes made in one go
It would look from what you screenshot that there is a simple $400 penalty for cancellation and so you would receive a refund of fare miinus $400 to form of payment
You are not down to any mercies - the various call centres are quite capable of proessing a simple cancellation, so no need to be disparaging towards them