Malindo Air complaint: Indescrepency with change of flights. Threatened forfeit

I called to querie the change of flight fee as online states $406 AUD , however their teams and condition state $80 per fee plus price difference of fare.
I spoke with a gentleman who states it was $236, I agreed and he sent me an online invoice for payment. Upon opening this I noticed this price was per passenger, which I was unaware of, I phoned them back to querie this, I was constantly put on silent hold and my queries were not addressed. I did curse at the woman when I thought she had hubgn up on me (she had put me on silent hold) she then proceeded to put me on silent hold, no one would help me. They told me unless I pay my invoice for $476 both tickets will be forfeit and void I have emailed trying to rectify this with no avail.
I even emailed stated to cancel the change of flight request. It was denied
Now because I won’t pay the $476 to change dates , they say I will loose both tickets (paid $804, current return tickets on my preferred dates at $714)
Please help me as not fair I loose these tickets