The category can matter more than the event
A birthday, graduation or end of studies may trigger a review of dependant status under scheme rules. The financial question is not simply when the life event happened, but which category applied on the contribution effective date.
Documents that clarify the timeline
Collect the amendment request, proof requested by the scheme, its receipt acknowledgement and the first invoice showing the changed amount. These establish what was asked, when it was received and when the contribution moved.
Ask one precise question
Instead of asking why the premium rose, ask the administrator to state the dependant category, effective date and contribution table line used. That answer is easier to test against the application record.
Rules differ between schemes and options. A financial audit can reconcile the captured category and figures, but cannot decide eligibility where the scheme rules reserve that decision.
Need a figure checked against your application? Ask for an independent contribution review.