I'm flying YVR-CPT in April, 2015. J class ticket was booked through AP. I had to adjust my flight back to YVR and am now flying a different route back with different airlines. I called AP and was advised of the change itinerary fee of $90. Not a big deal. I made the change and paid the fee. Here's my concern…

At no time was I made aware of the increase in YQ to the tune of about $400 to do so. This charge has now shown up on my CC.

Questions:
1) Do I have any argument with AP, as I was not made aware of the increase in YQ.
2) If so, any suggestions on how to approach AP to get a refund.

Thanks!
Afta.