Bonuses usually come with long strings attached. If you feel you are owed cash, don't accept a bonus as an alternative.
Explain to iForex that the FPA does not remove complaints, but can mark the complaints as resolved. Resolved is defined as paying all the money legitimately owed to the client. If iForex wants to claim they don't owe you this money, I would like them to come here and explain how they are calculating the totals.