Tripmonster complaint: Not applying my flexible ticket when asked

I have booked a one way ticket flight on July 1st through Tripmonster from Jordan to New York for $725 (including extra fees for seat selection and other services). I paid the extra money for the flexible flight option to be able to change the date if I needed to as advertised clearly on their website while your’e booking. Not too long after and due to health related issue with my mother, the date of flying needed to be changed, so I chose another date on July 30. I was surprised that Tripmonster customer service sent an email asking me to pay $744 extra to make the change of date requested on top of the $725 I already paid.

When I searched for the customer service number (not on Tripmonster website), I spoke with a lady who told me that the price difference on that date is ($744). I told her that it’s unreasonable for the price difference to be more expensive than the original ticket itself especially that the date chosen is still far away from the time it was requested. To proof my point, I simply made a quick search for a ticket on the future date desired and found a much cheaper ticket price than what they’re even asking for. The agent did not try to reason or help with making the change I requested.